chore: Kanmon Bridge 3.21.2 changelog.

fix(BRIDGE-406): fixed faulty certificate chain validation logic; made certificate pin checks exclusive to leaf certs;
chore: Kanmon Bridge 3.21.1 changelog.
2025-12-10 04:36:43 +00:00 · 2025-07-07 11:34:42 +02:00 · 2025-07-04 15:19:44 +02:00 · 2025-06-11 16:15:53 +02:00 · 2025-06-11 16:11:20 +02:00 · 2025-06-05 15:45:27 +02:00
108 changed files with 5705 additions and 435 deletions
--- a/.gitlab/CODEOWNERS
+++ b/.gitlab/CODEOWNERS
@ -1 +1 @@
-* @go/bridge-ppl/devs
+* inbox-desktop-approvers
--- a/BUILDS.md
+++ b/BUILDS.md
@ -3,14 +3,14 @@
 ## Prerequisites
 * 64-bit OS:
    - the go-rfc5322 module cannot currently be compiled for 32-bit OSes
-* Go 1.23.4
+* Go 1.24.0
 * Bash with basic build utils: make, gcc, sed, find, grep, ...
  - For Windows, it is recommended to use MinGW 64bit shell from [MSYS2](https://www.msys2.org/)
 * GCC (Linux), msvc (Windows) or Xcode (macOS)
 * Windres (Windows)
 * libglvnd and libsecret development files (Linux)
 * pkg-config (Linux)
-* cmake, ninja-build and Qt 6.4.3 are required to build the graphical user interface. On Linux, 
+* cmake, ninja-build and Qt 6.8.2 are required to build the graphical user interface. On Linux, 
 the Mesa OpenGL development files are also needed.

 To enable the sending of crash reports using Sentry please set the
@ -19,7 +19,7 @@ Otherwise, the sending of crash reports will be disabled.

 ## Build
 In order to build Bridge app with Qt interface we are using
-[Qt 6.4.3](https://doc.qt.io/qt-6/gettingstarted.html).
+[Qt 6.8.2](https://doc.qt.io/qt-6/gettingstarted.html).

 Please note that qmake path must be in your `PATH` to ensure Qt to be found.
 Also, before you start build **on Windows**, please unset the `MSYSTEM` variable
--- a/COPYING_NOTES.md
+++ b/COPYING_NOTES.md
@ -127,6 +127,7 @@ Proton Mail Bridge includes the following 3rd party software:
 * [blackfriday](https://github.com/russross/blackfriday/v2) available under [license](https://github.com/russross/blackfriday/v2/blob/master/LICENSE) 
 * [pflag](https://github.com/spf13/pflag) available under [license](https://github.com/spf13/pflag/blob/master/LICENSE) 
 * [bom](https://github.com/ssor/bom) available under [license](https://github.com/ssor/bom/blob/master/LICENSE) 
+* [objx](https://github.com/stretchr/objx) available under [license](https://github.com/stretchr/objx/blob/master/LICENSE) 
 * [golang-asm](https://github.com/twitchyliquid64/golang-asm) available under [license](https://github.com/twitchyliquid64/golang-asm/blob/master/LICENSE) 
 * [codec](https://github.com/ugorji/go/codec) available under [license](https://github.com/ugorji/go/codec/blob/master/LICENSE) 
 * [tagparser](https://github.com/vmihailenco/tagparser/v2) available under [license](https://github.com/vmihailenco/tagparser/v2/blob/master/LICENSE) 
@ -141,6 +142,7 @@ Proton Mail Bridge includes the following 3rd party software:
 * [appengine](https://google.golang.org/appengine) available under [license](https://pkg.go.dev/google.golang.org/appengine?tab=licenses) 
 * [genproto](https://google.golang.org/genproto) available under [license](https://pkg.go.dev/google.golang.org/genproto?tab=licenses) 
 * [yaml](https://gopkg.in/yaml.v3) available under [license](https://github.com/go-yaml/yaml/blob/v3.0.1/LICENSE)  available under [license](https://github.com/go-yaml/yaml/blob/v3.0.1/LICENSE) 
+* [go-autostart](https://github.com/ElectroNafta/go-autostart) available under [license](https://github.com/ElectroNafta/go-autostart/blob/master/LICENSE) 
 * [go-message](https://github.com/ProtonMail/go-message) available under [license](https://github.com/ProtonMail/go-message/blob/master/LICENSE) 
 * [go-smtp](https://github.com/ProtonMail/go-smtp) available under [license](https://github.com/ProtonMail/go-smtp/blob/master/LICENSE) 
 * [resty](https://github.com/LBeernaertProton/resty/v2) available under [license](https://github.com/LBeernaertProton/resty/v2/blob/master/LICENSE) 
--- a/Changelog.md
+++ b/Changelog.md
@ -3,6 +3,93 @@
 Changelog [format](http://keepachangelog.com/en/1.0.0/)


+## Kanmon Bridge 3.21.2
+
+### Fixed
+* BRIDGE-406: Fixed faulty certificate chain validation logic. Made certificate pin checks exclusive to leaf certificates.
+
+
+## Kanmon Bridge 3.21.1
+
+### Changed
+* BRIDGE-383: Extended internal mailbox conflict resolution logic and minor changes to the mailbox conflict pre-checker. 
+
+
+## Kanmon Bridge 3.21.0
+
+### Added 
+* BRIDGE-379: Mailbox pre-check on Bridge startup & conflict resolver for Bridge internal mailboxes. 
+
+### Changed
+* BRIDGE-376: Explicitly catch Gluon DB mailbox name conflicts and report them to Sentry.
+* BRIDGE-373: Extend user mailbox conflict resolver logging & report sync errors to Sentry.
+* BRIDGE-366: Kill switch support for IMAP IDLE.
+* BRIDGE-363: Observability metric support for IMAP connections.
+
+### Fixed
+* BRIDGE-377: Correct API label field usage on user label conflict resolver - update handler (event loop).
+* BRIDGE-378: Fix incorrect field usage for system mailbox names.
+
+
+## Jubilee Bridge 3.20.1
+
+### Fixed
+* BRIDGE-362: Implemented logic for reconciling label conflicts.
+
+
+## Jubilee Bridge 3.20.0
+
+### Added
+* BRIDGE-348: Enable display of BYOE addresses in Bridge.
+* BRIDGE-340: Added additional logging for label operations and related bad events.
+* BRIDGE-324: Log a hash of the vault key on Bridge start.
+
+### Changed
+* BRIDGE-352: Chore: bump go to 1.24.2.
+* BRIDGE-353: Chore: update x/net package to 0.38.0.
+
+### Fixed
+* BRIDGE-351: Allow draft creation and import to BYOE addresses in combined mode.
+* BRIDGE-301: Prevent imports into non-BYOE external addresses.
+* BRIDGE-341: Replaced go-autostart with a fork to support creating autostart shortcuts in directories with Unicode characters on Windows.
+* BRIDGE-332: Strip newline characters from username and password fields in the Bridge GUI.
+* BRIDGE-336: Ensure all remote labels are verified and created in Gluon at Bridge startup.
+* BRIDGE-335: Persist the last successfully used keychain helper as a user preference on Linux.
+* BRIDGE-333: Ignore unknown label IDs during Bridge synchronization.
+
+
+## Infinity Bridge 3.19.0
+
+### Changed
+* BRIDGE-316: Update Qt to latest LTS version 6.8.2.
+
+
+## Helix Bridge 3.18.0
+
+### Changed
+* BRIDGE-309: Revised update logic and structure.
+* BRIDGE-154: Added access token to expiry refresh request.
+
+
+## Grunwald Bridge 3.17.0
+
+### Added
+* BRIDGE-271: Report version file check failure to Sentry.
+* BRIDGE-247: Test: Automate Bridge 0% update rollout.
+* BRIDGE-248: Test: Additional Bridge UI e2e automation tests.
+
+### Changed
+* BRIDGE-73: Update goopenpgp.
+* BRIDGE-287: Update x/net and x/crypto dependencies.
+* BRIDGE-303: Update govulncheck to latest release.
+* BRIDGE-226: Bump Go version to 1.23.4.
+* BRIDGE-288: Extension to synchronization update handler, observability tweaks and gluon update.
+
+### Fixed
+* BRIDGE-291: Use correct field for user plan type.
+* BRIDGE-143: Add missing QML component attribute, cut/paste disabled on read-only text areas.
+
+
 ## Flavien Bridge 3.16.0

 ### Added
--- a/4
+++ b/4
@ -12,7 +12,7 @@ ROOT_DIR:=$(realpath .)
 .PHONY: build build-gui build-nogui build-launcher versioner hasher

 # Keep version hardcoded so app build works also without Git repository.
-BRIDGE_APP_VERSION?=3.16.0+git
+BRIDGE_APP_VERSION?=3.21.2+git
 APP_VERSION:=${BRIDGE_APP_VERSION}
 APP_FULL_NAME:=Proton Mail Bridge
 APP_VENDOR:=Proton AG
@ -189,7 +189,7 @@ ${RESOURCE_FILE}: ./dist/info.rc ./dist/${SRC_ICO} .FORCE

 ## Dev dependencies
 .PHONY: install-devel-tools install-linter install-go-mod-outdated install-git-hooks
-LINTVER:="v1.61.0"
+LINTVER:="v1.64.6"
 LINTSRC:="https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh"

 install-dev-dependencies: install-devel-tools install-linter install-go-mod-outdated
--- a/go.mod
+++ b/go.mod
@ -1,15 +1,15 @@
 module github.com/ProtonMail/proton-bridge/v3

-go 1.23
+go 1.24

-toolchain go1.23.4
+toolchain go1.24.2

 require (
 	github.com/0xAX/notificator v0.0.0-20220220101646-ee9b8921e557
 	github.com/Masterminds/semver/v3 v3.2.0
-	github.com/ProtonMail/gluon v0.17.1-0.20250116113909-2ebd96ec0bc2
+	github.com/ProtonMail/gluon v0.17.1-0.20250611120816-05167d499f8d
 	github.com/ProtonMail/go-autostart v0.0.0-20210130080809-00ed301c8e9a
-	github.com/ProtonMail/go-proton-api v0.4.1-0.20250121114701-67bd01ad0bc3
+	github.com/ProtonMail/go-proton-api v0.4.1-0.20250417134000-e624a080f7ba
 	github.com/ProtonMail/gopenpgp/v2 v2.8.2-proton
 	github.com/PuerkitoBio/goquery v1.8.1
 	github.com/abiosoft/ishell v2.0.0+incompatible
@ -46,10 +46,10 @@ require (
 	github.com/vmihailenco/msgpack/v5 v5.3.5
 	go.uber.org/goleak v1.2.1
 	golang.org/x/exp v0.0.0-20230522175609-2e198f4a06a1
-	golang.org/x/net v0.34.0
+	golang.org/x/net v0.38.0
 	golang.org/x/oauth2 v0.7.0
-	golang.org/x/sys v0.29.0
-	golang.org/x/text v0.21.0
+	golang.org/x/sys v0.31.0
+	golang.org/x/text v0.23.0
 	google.golang.org/api v0.114.0
 	google.golang.org/grpc v1.56.3
 	google.golang.org/protobuf v1.33.0
@ -114,6 +114,7 @@ require (
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
 	github.com/ssor/bom v0.0.0-20170718123548-6386211fdfcf // indirect
+	github.com/stretchr/objx v0.5.0 // indirect
 	github.com/twitchyliquid64/golang-asm v0.15.1 // indirect
 	github.com/ugorji/go/codec v1.2.11 // indirect
 	github.com/vmihailenco/tagparser/v2 v2.0.0 // indirect
@ -121,9 +122,9 @@ require (
 	gitlab.com/c0b/go-ordered-json v0.0.0-20201030195603-febf46534d5a // indirect
 	go.opencensus.io v0.24.0 // indirect
 	golang.org/x/arch v0.3.0 // indirect
-	golang.org/x/crypto v0.32.0 // indirect
+	golang.org/x/crypto v0.36.0 // indirect
 	golang.org/x/mod v0.17.0 // indirect
-	golang.org/x/sync v0.10.0 // indirect
+	golang.org/x/sync v0.12.0 // indirect
 	golang.org/x/tools v0.21.1-0.20240508182429-e35e4ccd0d2d // indirect
 	google.golang.org/appengine v1.6.7 // indirect
 	google.golang.org/genproto v0.0.0-20230410155749-daa745c078e1 // indirect
@ -131,6 +132,7 @@ require (
 )

 replace (
+	github.com/ProtonMail/go-autostart => github.com/ElectroNafta/go-autostart v0.0.0-20250402094843-326608c16033
 	github.com/emersion/go-message => github.com/ProtonMail/go-message v0.13.1-0.20240919135104-3bc88e6a9423
 	github.com/emersion/go-smtp => github.com/ProtonMail/go-smtp v0.0.0-20231109081432-2b3d50599865
 	github.com/go-resty/resty/v2 => github.com/LBeernaertProton/resty/v2 v2.0.0-20231129100320-dddf8030d93a
--- a/go.sum
+++ b/go.sum
@ -23,6 +23,8 @@ github.com/0xAX/notificator v0.0.0-20220220101646-ee9b8921e557 h1:l6surSnJ3RP4qA
 github.com/0xAX/notificator v0.0.0-20220220101646-ee9b8921e557/go.mod h1:sTrmvD/TxuypdOERsDOS7SndZg0rzzcCi1b6wQMXUYM=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
+github.com/ElectroNafta/go-autostart v0.0.0-20250402094843-326608c16033 h1:d2RB9rQmSusb0K+qSgB+DAY+8i+AXZ/o+oDHj2vAUaA=
+github.com/ElectroNafta/go-autostart v0.0.0-20250402094843-326608c16033/go.mod h1:o0nKiWcK0e2G/90uL6akWRkzOV4mFcZmvpBPpigJvdw=
 github.com/Kodeworks/golang-image-ico v0.0.0-20141118225523-73f0f4cfade9/go.mod h1:7uhhqiBaR4CpN0k9rMjOtjpcfGd6DG2m04zQxKnWQ0I=
 github.com/LBeernaertProton/resty/v2 v2.0.0-20231129100320-dddf8030d93a h1:eQO/GF/+H8/9udc9QAgieFr+jr1tjXlJo35RAhsUbWY=
 github.com/LBeernaertProton/resty/v2 v2.0.0-20231129100320-dddf8030d93a/go.mod h1:iiP/OpA0CkcL3IGt1O0+/SIItFUbkkyw5BGXiVdTu+A=
@ -34,10 +36,8 @@ github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAE
 github.com/ProtonMail/bcrypt v0.0.0-20210511135022-227b4adcab57/go.mod h1:HecWFHognK8GfRDGnFQbW/LiV7A3MX3gZVs45vk5h8I=
 github.com/ProtonMail/bcrypt v0.0.0-20211005172633-e235017c1baf h1:yc9daCCYUefEs69zUkSzubzjBbL+cmOXgnmt9Fyd9ug=
 github.com/ProtonMail/bcrypt v0.0.0-20211005172633-e235017c1baf/go.mod h1:o0ESU9p83twszAU8LBeJKFAAMX14tISa0yk4Oo5TOqo=
-github.com/ProtonMail/gluon v0.17.1-0.20250116113909-2ebd96ec0bc2 h1:lDgMidI/9j2eedavcy7YICv8+F73ooVTUoUGBE4dO0s=
-github.com/ProtonMail/gluon v0.17.1-0.20250116113909-2ebd96ec0bc2/go.mod h1:0/c03TzZPNiSgY5UDJK1iRDkjlDPwWugxTT6et2qDu8=
-github.com/ProtonMail/go-autostart v0.0.0-20210130080809-00ed301c8e9a h1:D+aZah+k14Gn6kmL7eKxoo/4Dr/lK3ChBcwce2+SQP4=
-github.com/ProtonMail/go-autostart v0.0.0-20210130080809-00ed301c8e9a/go.mod h1:oTGdE7/DlWIr23G0IKW3OXK9wZ5Hw1GGiaJFccTvZi4=
+github.com/ProtonMail/gluon v0.17.1-0.20250611120816-05167d499f8d h1:45W7G+X0w7nzLzeB0eiFkGho5DTK1jNmmNbt3IhN524=
+github.com/ProtonMail/gluon v0.17.1-0.20250611120816-05167d499f8d/go.mod h1:0/c03TzZPNiSgY5UDJK1iRDkjlDPwWugxTT6et2qDu8=
 github.com/ProtonMail/go-crypto v0.0.0-20230321155629-9a39f2531310/go.mod h1:8TI4H3IbrackdNgv+92dI+rhpCaLqM0IfpgCgenFvRE=
 github.com/ProtonMail/go-crypto v1.1.4-proton h1:KIo9uNlk3vzlwI7o5VjhiEjI4Ld1TDixOMnoNZyfpFE=
 github.com/ProtonMail/go-crypto v1.1.4-proton/go.mod h1:zNoyBJW3p/yVWiHNZgfTF9VsjwqYof5YY0M9kt2QaX0=
@ -45,8 +45,8 @@ github.com/ProtonMail/go-message v0.13.1-0.20240919135104-3bc88e6a9423 h1:p8nBDx
 github.com/ProtonMail/go-message v0.13.1-0.20240919135104-3bc88e6a9423/go.mod h1:NBAn21zgCJ/52WLDyed18YvYFm5tEoeDauubFqLokM4=
 github.com/ProtonMail/go-mime v0.0.0-20230322103455-7d82a3887f2f h1:tCbYj7/299ekTTXpdwKYF8eBlsYsDVoggDAuAjoK66k=
 github.com/ProtonMail/go-mime v0.0.0-20230322103455-7d82a3887f2f/go.mod h1:gcr0kNtGBqin9zDW9GOHcVntrwnjrK+qdJ06mWYBybw=
-github.com/ProtonMail/go-proton-api v0.4.1-0.20250121114701-67bd01ad0bc3 h1:YYnLBVcg7WrEbYVmF1PBr4AEQlob9rCphsMHAmF4CAo=
-github.com/ProtonMail/go-proton-api v0.4.1-0.20250121114701-67bd01ad0bc3/go.mod h1:RYgagBFkA3zFrSt7/vviFFwjZxBo6pGzcTwFsLwsnyc=
+github.com/ProtonMail/go-proton-api v0.4.1-0.20250417134000-e624a080f7ba h1:DFBngZ7u/f69flRFzPp6Ipo6PKEyflJlA5OCh52yDB4=
+github.com/ProtonMail/go-proton-api v0.4.1-0.20250417134000-e624a080f7ba/go.mod h1:eXIoLyIHxvPo8Kd9e1ygYIrAwbeWJhLi3vgSz2crlK4=
 github.com/ProtonMail/go-smtp v0.0.0-20231109081432-2b3d50599865 h1:EP1gnxLL5Z7xBSymE9nSTM27nRYINuvssAtDmG0suD8=
 github.com/ProtonMail/go-smtp v0.0.0-20231109081432-2b3d50599865/go.mod h1:qm27SGYgoIPRot6ubfQ/GpiPy/g3PaZAVRxiO/sDUgQ=
 github.com/ProtonMail/go-srp v0.0.7 h1:Sos3Qk+th4tQR64vsxGIxYpN3rdnG9Wf9K4ZloC1JrI=
@ -498,8 +498,8 @@ golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPh
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/crypto v0.7.0/go.mod h1:pYwdfH91IfpZVANVyUOhSIPZaFoJGxTFbZhFTx+dXZU=
 golang.org/x/crypto v0.14.0/go.mod h1:MVFd36DqK4CsrnJYDkBA3VC4m2GkXAM0PvzMCn4JQf4=
-golang.org/x/crypto v0.32.0 h1:euUpcYgM8WcP71gNpTqQCn6rC2t6ULUPiOzfWaXVVfc=
-golang.org/x/crypto v0.32.0/go.mod h1:ZnnJkOaASj8g0AjIduWNlq2NRxL0PlBrbKVyZ6V/Ugc=
+golang.org/x/crypto v0.36.0 h1:AnAEvhDddvBdpY+uR+MyHmuZzzNqXSe/GvuDeob5L34=
+golang.org/x/crypto v0.36.0/go.mod h1:Y4J0ReaxCR1IMaabaSMugxJES1EpwhBHhv2bDHklZvc=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190306152737-a1d7652674e8/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190510132918-efd6b22b2522/go.mod h1:ZjyILWgesfNpC6sMxTJOJm9Kp84zZh5NQWvqDGG3Qr8=
@ -555,8 +555,8 @@ golang.org/x/net v0.8.0/go.mod h1:QVkue5JL9kW//ek3r6jTKnTFis1tRmNAW2P1shuFdJc=
 golang.org/x/net v0.9.0/go.mod h1:d48xBJpPfHeWQsugry2m+kC02ZBRGRgulfHnEXEuWns=
 golang.org/x/net v0.10.0/go.mod h1:0qNGK6F8kojg2nk9dLZ2mShWaEBan6FAoqfSigmmuDg=
 golang.org/x/net v0.17.0/go.mod h1:NxSsAGuq816PNPmqtQdLE42eU2Fs7NoRIZrHJAlaCOE=
-golang.org/x/net v0.34.0 h1:Mb7Mrk043xzHgnRM88suvJFwzVrRfHEHJEl5/71CKw0=
-golang.org/x/net v0.34.0/go.mod h1:di0qlW3YNM5oh6GqDGQr92MyTozJPmybPK4Ev/Gm31k=
+golang.org/x/net v0.38.0 h1:vRMAPTMaeGqVhG5QyLJHqNDwecKTomGeqbnfZyKlBI8=
+golang.org/x/net v0.38.0/go.mod h1:ivrbrMbzFq5J41QOQh0siUuly180yBYtLp+CKbEaFx8=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20190226205417-e64efc72b421/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
@ -571,8 +571,8 @@ golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.10.0 h1:3NQrjDixjgGwUOCaF8w2+VYHv0Ve/vGYSbdkTa98gmQ=
-golang.org/x/sync v0.10.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
+golang.org/x/sync v0.12.0 h1:MHc5BpPuC30uJk597Ri8TV3CNZcTLu6B6z4lJy+g6Jw=
+golang.org/x/sync v0.12.0/go.mod h1:1dzgHSNfp02xaA81J2MS99Qcpr2w7fw1gpm99rleRqA=
 golang.org/x/sys v0.0.0-20180823144017-11551d06cbcc/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
@ -611,8 +611,8 @@ golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.7.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.8.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.13.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.29.0 h1:TPYlXGxvx1MGTn2GiZDhnjPA9wZzZeGKHHmKhHYvgaU=
-golang.org/x/sys v0.29.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.31.0 h1:ioabZlmFYtWhL+TRYpcnNlLwhyxaM9kWTDEmfnprqik=
+golang.org/x/sys v0.31.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k=
@ -632,8 +632,8 @@ golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
 golang.org/x/text v0.8.0/go.mod h1:e1OnstbJyHTd6l/uOt8jFFHp6TRDWZR/bV3emEE/zU8=
 golang.org/x/text v0.9.0/go.mod h1:e1OnstbJyHTd6l/uOt8jFFHp6TRDWZR/bV3emEE/zU8=
 golang.org/x/text v0.13.0/go.mod h1:TvPlkZtksWOMsz7fbANvkp4WM8x/WCo/om8BMLbz+aE=
-golang.org/x/text v0.21.0 h1:zyQAAkrwaneQ066sspRyJaG9VNi/YJ1NfzcGB3hZ/qo=
-golang.org/x/text v0.21.0/go.mod h1:4IBbMaMmOPCJ8SecivzSH54+73PCFmPWxNTLm+vZkEQ=
+golang.org/x/text v0.23.0 h1:D71I7dUrlY+VX0gQShAThNGHFxZ13dGLBHQLVl1mJlY=
+golang.org/x/text v0.23.0/go.mod h1:/BLNzu4aZCJ1+kcD0DNRotWKage4q2rGVAg4o22unh4=
 golang.org/x/time v0.0.0-20181108054448-85acf8d2951c/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.0.0-20190308202827-9d24e82272b4/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.3.0 h1:rg5rLMjNzMS1RkNLzCG38eapWhnYLFYXDXj2gOlr8j4=
--- a/internal/app/migration.go
+++ b/internal/app/migration.go
@ -138,7 +138,7 @@ func migrateOldAccounts(locations *locations.Locations, keychains *keychain.List
 	if err != nil {
 		return fmt.Errorf("failed to get helper: %w", err)
 	}
-	keychain, err := keychain.NewKeychain(helper, "bridge", keychains.GetHelpers(), keychains.GetDefaultHelper())
+	keychain, _, err := keychain.NewKeychain(helper, "bridge", keychains.GetHelpers(), keychains.GetDefaultHelper())
 	if err != nil {
 		return fmt.Errorf("failed to create keychain: %w", err)
 	}
--- a/internal/app/migration_test.go
+++ b/internal/app/migration_test.go
@ -134,7 +134,7 @@ func TestKeychainMigration(t *testing.T) {
 func TestUserMigration(t *testing.T) {
 	kcl := keychain.NewTestKeychainsList()

-	kc, err := keychain.NewKeychain("mock", "bridge", kcl.GetHelpers(), kcl.GetDefaultHelper())
+	kc, _, err := keychain.NewKeychain("mock", "bridge", kcl.GetHelpers(), kcl.GetDefaultHelper())
 	require.NoError(t, err)

 	require.NoError(t, kc.Put("brokenID", "broken"))
--- a/internal/app/vault.go
+++ b/internal/app/vault.go
@ -18,6 +18,8 @@
 package app

 import (
+	"crypto/sha256"
+	"encoding/hex"
 	"fmt"
 	"path"

@ -67,11 +69,12 @@ func newVault(reporter *sentry.Reporter, locations *locations.Locations, keychai
 	logrus.WithField("vaultDir", vaultDir).Debug("Loading vault from directory")

 	var (
-		vaultKey []byte
-		insecure bool
+		vaultKey       []byte
+		insecure       bool
+		lastUsedHelper string
 	)

-	if key, err := loadVaultKey(vaultDir, keychains); err != nil {
+	if key, helper, err := loadVaultKey(vaultDir, keychains); err != nil {
 		if reporter != nil {
 			if rerr := reporter.ReportMessageWithContext("Could not load/create vault key", map[string]any{
 				"keychainDefaultHelper":       keychains.GetDefaultHelper(),
@ -89,6 +92,8 @@ func newVault(reporter *sentry.Reporter, locations *locations.Locations, keychai
 		vaultDir = path.Join(vaultDir, "insecure")
 	} else {
 		vaultKey = key
+		lastUsedHelper = helper
+		logHashedVaultKey(vaultKey) // Log a hash of the vault key.
 	}

 	gluonCacheDir, err := locations.ProvideGluonCachePath()
@ -96,34 +101,47 @@ func newVault(reporter *sentry.Reporter, locations *locations.Locations, keychai
 		return nil, false, nil, fmt.Errorf("could not provide gluon path: %w", err)
 	}

-	vault, corrupt, err := vault.New(vaultDir, gluonCacheDir, vaultKey, panicHandler)
+	userVault, corrupt, err := vault.New(vaultDir, gluonCacheDir, vaultKey, panicHandler)
 	if err != nil {
 		return nil, false, corrupt, fmt.Errorf("could not create vault: %w", err)
 	}

-	return vault, insecure, corrupt, nil
+	// Remember the last successfully used keychain and store that as the user preference.
+	if err := vault.SetHelper(vaultDir, lastUsedHelper); err != nil {
+		logrus.WithError(err).Error("Could not store last used keychain helper")
+	}
+
+	return userVault, insecure, corrupt, nil
 }

-func loadVaultKey(vaultDir string, keychains *keychain.List) ([]byte, error) {
-	helper, err := vault.GetHelper(vaultDir)
+// loadVaultKey - loads the key used to encrypt the vault alongside the keychain helper used to access it.
+func loadVaultKey(vaultDir string, keychains *keychain.List) (key []byte, keychainHelper string, err error) {
+	keychainHelper, err = vault.GetHelper(vaultDir)
 	if err != nil {
-		return nil, fmt.Errorf("could not get keychain helper: %w", err)
+		return nil, keychainHelper, fmt.Errorf("could not get keychain helper: %w", err)
 	}

-	kc, err := keychain.NewKeychain(helper, constants.KeyChainName, keychains.GetHelpers(), keychains.GetDefaultHelper())
+	kc, keychainHelper, err := keychain.NewKeychain(keychainHelper, constants.KeyChainName, keychains.GetHelpers(), keychains.GetDefaultHelper())
 	if err != nil {
-		return nil, fmt.Errorf("could not create keychain: %w", err)
+		return nil, keychainHelper, fmt.Errorf("could not create keychain: %w", err)
 	}

-	key, err := vault.GetVaultKey(kc)
+	key, err = vault.GetVaultKey(kc)
 	if err != nil {
 		if keychain.IsErrKeychainNoItem(err) {
 			logrus.WithError(err).Warn("no vault key found, generating new")
-			return vault.NewVaultKey(kc)
+			key, err := vault.NewVaultKey(kc)
+			return key, keychainHelper, err
 		}

-		return nil, fmt.Errorf("could not check for vault key: %w", err)
+		return nil, keychainHelper, fmt.Errorf("could not check for vault key: %w", err)
 	}

-	return key, nil
+	return key, keychainHelper, nil
+}
+
+// logHashedVaultKey - computes a sha256 hash and encodes it to base 64. The resulting string is logged.
+func logHashedVaultKey(vaultKey []byte) {
+	hashedKey := sha256.Sum256(vaultKey)
+	logrus.WithField("hashedKey", hex.EncodeToString(hashedKey[:])).Info("Found vault key")
 }
--- a/internal/bridge/bridge.go
+++ b/internal/bridge/bridge.go
@ -55,6 +55,7 @@ import (
 	"github.com/ProtonMail/proton-bridge/v3/internal/vault"
 	"github.com/ProtonMail/proton-bridge/v3/pkg/keychain"
 	"github.com/bradenaw/juniper/xslices"
+	"github.com/elastic/go-sysinfo/types"
 	"github.com/go-resty/resty/v2"
 	"github.com/sirupsen/logrus"
 )
@ -81,8 +82,9 @@ type Bridge struct {
 	imapEventCh chan imapEvents.Event

 	// updater is the bridge's updater.
-	updater   Updater
-	installCh chan installJob
+	updater         Updater
+	installChLegacy chan installJobLegacy
+	installCh       chan installJob

 	// heartbeat is the telemetry heartbeat for metrics.
 	heartbeat *heartBeatState
@ -149,6 +151,9 @@ type Bridge struct {

 	// notificationStore is used for notification deduplication
 	notificationStore *notifications.Store
+
+	// getHostVersion primarily used for testing the update logic - it should return an OS version
+	getHostVersion func(host types.Host) string
 }

 var logPkg = logrus.WithField("pkg", "bridge") //nolint:gochecknoglobals
@ -283,8 +288,9 @@ func newBridge(
 		tlsConfig:   tlsConfig,
 		imapEventCh: imapEventCh,

-		updater:   updater,
-		installCh: make(chan installJob),
+		updater:         updater,
+		installChLegacy: make(chan installJobLegacy),
+		installCh:       make(chan installJob),

 		curVersion:     curVersion,
 		newVersion:     curVersion,
@ -316,6 +322,8 @@ func newBridge(
 		observabilityService: observabilityService,

 		notificationStore: notifications.NewStore(locator.ProvideNotificationsCachePath),
+
+		getHostVersion: func(host types.Host) string { return host.Info().OS.Version },
 	}

 	bridge.serverManager = imapsmtpserver.NewService(context.Background(),
@ -327,6 +335,7 @@ func newBridge(
 		uidValidityGenerator,
 		&bridgeIMAPSMTPTelemetry{b: bridge},
 		observabilityService,
+		unleashService,
 	)

 	// Check whether username has changed and correct (macOS only)
@ -436,8 +445,17 @@ func (bridge *Bridge) init(tlsReporter TLSReporter) error {
 	// Check for updates when triggered.
 	bridge.goUpdate = bridge.tasks.PeriodicOrTrigger(constants.UpdateCheckInterval, 0, func(ctx context.Context) {
 		logPkg.Info("Checking for updates")
+		var versionLegacy updater.VersionInfoLegacy
+		var version updater.VersionInfo
+		var err error
+
+		useOldUpdateLogic := bridge.GetFeatureFlagValue(unleash.UpdateUseNewVersionFileStructureDisabled)
+		if useOldUpdateLogic {
+			versionLegacy, err = bridge.updater.GetVersionInfoLegacy(ctx, bridge.api, bridge.vault.GetUpdateChannel())
+		} else {
+			version, err = bridge.updater.GetVersionInfo(ctx, bridge.api)
+		}

-		version, err := bridge.updater.GetVersionInfo(ctx, bridge.api, bridge.vault.GetUpdateChannel())
 		if err != nil {
 			bridge.publish(events.UpdateCheckFailed{Error: err})
 			if errors.Is(err, updater.ErrVersionFileDownloadOrVerify) {
@ -450,12 +468,23 @@ func (bridge *Bridge) init(tlsReporter TLSReporter) error {
 				}
 			}
 		} else {
-			bridge.handleUpdate(version)
+			if useOldUpdateLogic {
+				bridge.handleUpdateLegacy(versionLegacy)
+			} else {
+				bridge.handleUpdate(version)
+			}
 		}
 	})
 	defer bridge.goUpdate()

-	// Install updates when available.
+	// Install updates when available - based on old update logic
+	bridge.tasks.Once(func(ctx context.Context) {
+		async.RangeContext(ctx, bridge.installChLegacy, func(job installJobLegacy) {
+			bridge.installUpdateLegacy(ctx, job)
+		})
+	})
+
+	// Install updates when available - based on new update logic
 	bridge.tasks.Once(func(ctx context.Context) {
 		async.RangeContext(ctx, bridge.installCh, func(job installJob) {
 			bridge.installUpdate(ctx, job)
@ -692,13 +721,13 @@ func (bridge *Bridge) verifyUsernameChange() {
 func GetUpdatedCachePath(gluonDBPath, gluonCachePath string) string {
 	// If gluon cache is moved to an external drive; regex find will fail; as is expected
 	cachePathMatches := usernameChangeRegex.FindStringSubmatch(gluonCachePath)
-	if cachePathMatches == nil || len(cachePathMatches) < 2 {
+	if len(cachePathMatches) < 2 {
 		return ""
 	}

 	cacheUsername := cachePathMatches[1]
 	dbPathMatches := usernameChangeRegex.FindStringSubmatch(gluonDBPath)
-	if dbPathMatches == nil || len(dbPathMatches) < 2 {
+	if len(dbPathMatches) < 2 {
 		return ""
 	}

@ -718,7 +747,7 @@ func (bridge *Bridge) PushObservabilityMetric(metric proton.ObservabilityMetric)
 	bridge.observabilityService.AddMetrics(metric)
 }

-func (bridge *Bridge) PushDistinctObservabilityMetrics(errType observability.DistinctionErrorTypeEnum, metrics ...proton.ObservabilityMetric) {
+func (bridge *Bridge) PushDistinctObservabilityMetrics(errType observability.DistinctionMetricTypeEnum, metrics ...proton.ObservabilityMetric) {
 	bridge.observabilityService.AddDistinctMetrics(errType, metrics...)
 }

@ -740,3 +769,19 @@ func (bridge *Bridge) ReportMessageWithContext(message string, messageCtx report
 func (bridge *Bridge) GetUsers() map[string]*user.User {
 	return bridge.users
 }
+
+// SetCurrentVersionTest - sets the current version of bridge; should only be used for tests.
+func (bridge *Bridge) SetCurrentVersionTest(version *semver.Version) {
+	bridge.curVersion = version
+	bridge.newVersion = version
+}
+
+// SetHostVersionGetterTest - sets the OS version helper func; only used for testing.
+func (bridge *Bridge) SetHostVersionGetterTest(fn func(host types.Host) string) {
+	bridge.getHostVersion = fn
+}
+
+// SetRolloutPercentageTest - sets the rollout percentage; should only be used for testing.
+func (bridge *Bridge) SetRolloutPercentageTest(rollout float64) error {
+	return bridge.vault.SetUpdateRollout(rollout)
+}
--- a/internal/bridge/bridge_test.go
+++ b/internal/bridge/bridge_test.go
@ -45,6 +45,7 @@ import (
 	"github.com/ProtonMail/proton-bridge/v3/internal/focus"
 	"github.com/ProtonMail/proton-bridge/v3/internal/locations"
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/imapsmtpserver"
+	"github.com/ProtonMail/proton-bridge/v3/internal/unleash"
 	"github.com/ProtonMail/proton-bridge/v3/internal/updater"
 	"github.com/ProtonMail/proton-bridge/v3/internal/user"
 	"github.com/ProtonMail/proton-bridge/v3/internal/useragent"
@ -383,9 +384,14 @@ func TestBridge_Cookies(t *testing.T) {
 	})
 }

-func TestBridge_CheckUpdate(t *testing.T) {
+func TestBridge_CheckUpdate_Legacy(t *testing.T) {
 	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridge.Locator, vaultKey []byte) {
+		unleash.ModifyPollPeriodAndJitter(500*time.Millisecond, 0)
+		s.PushFeatureFlag(unleash.UpdateUseNewVersionFileStructureDisabled)
+
 		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, vaultKey, func(bridge *bridge.Bridge, mocks *bridge.Mocks) {
+			// Wait for FF poll.
+			time.Sleep(600 * time.Millisecond)
 			// Disable autoupdate for this test.
 			require.NoError(t, bridge.SetAutoUpdate(false))

@ -400,7 +406,7 @@ func TestBridge_CheckUpdate(t *testing.T) {
 			require.Equal(t, events.UpdateNotAvailable{}, <-noUpdateCh)

 			// Simulate a new version being available.
-			mocks.Updater.SetLatestVersion(v2_4_0, v2_3_0)
+			mocks.Updater.SetLatestVersionLegacy(v2_4_0, v2_3_0)

 			// Get a stream of update available events.
 			updateCh, done := bridge.GetEvents(events.UpdateAvailable{})
@ -411,7 +417,7 @@ func TestBridge_CheckUpdate(t *testing.T) {

 			// We should receive an event indicating that an update is available.
 			require.Equal(t, events.UpdateAvailable{
-				Version: updater.VersionInfo{
+				VersionLegacy: updater.VersionInfoLegacy{
 					Version:           v2_4_0,
 					MinAuto:           v2_3_0,
 					RolloutProportion: 1.0,
@ -423,25 +429,30 @@ func TestBridge_CheckUpdate(t *testing.T) {
 	})
 }

-func TestBridge_AutoUpdate(t *testing.T) {
+func TestBridge_AutoUpdate_Legacy(t *testing.T) {
 	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridge.Locator, vaultKey []byte) {
-		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, vaultKey, func(bridge *bridge.Bridge, mocks *bridge.Mocks) {
+		unleash.ModifyPollPeriodAndJitter(500*time.Millisecond, 0)
+		s.PushFeatureFlag(unleash.UpdateUseNewVersionFileStructureDisabled)
+
+		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, vaultKey, func(b *bridge.Bridge, mocks *bridge.Mocks) {
+			// Wait for FF poll.
+			time.Sleep(600 * time.Millisecond)
 			// Enable autoupdate for this test.
-			require.NoError(t, bridge.SetAutoUpdate(true))
+			require.NoError(t, b.SetAutoUpdate(true))

 			// Get a stream of update events.
-			updateCh, done := bridge.GetEvents(events.UpdateInstalled{})
+			updateCh, done := b.GetEvents(events.UpdateInstalled{})
 			defer done()

 			// Simulate a new version being available.
-			mocks.Updater.SetLatestVersion(v2_4_0, v2_3_0)
+			mocks.Updater.SetLatestVersionLegacy(v2_4_0, v2_3_0)

 			// Check for updates.
-			bridge.CheckForUpdates()
+			b.CheckForUpdates()

 			// We should receive an event indicating that the update was silently installed.
 			require.Equal(t, events.UpdateInstalled{
-				Version: updater.VersionInfo{
+				VersionLegacy: updater.VersionInfoLegacy{
 					Version:           v2_4_0,
 					MinAuto:           v2_3_0,
 					RolloutProportion: 1.0,
@ -452,9 +463,14 @@ func TestBridge_AutoUpdate(t *testing.T) {
 	})
 }

-func TestBridge_ManualUpdate(t *testing.T) {
+func TestBridge_ManualUpdate_Legacy(t *testing.T) {
 	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridge.Locator, vaultKey []byte) {
+		unleash.ModifyPollPeriodAndJitter(500*time.Millisecond, 0)
+		s.PushFeatureFlag(unleash.UpdateUseNewVersionFileStructureDisabled)
+
 		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, vaultKey, func(bridge *bridge.Bridge, mocks *bridge.Mocks) {
+			// Wait for FF poll.
+			time.Sleep(600 * time.Millisecond)
 			// Disable autoupdate for this test.
 			require.NoError(t, bridge.SetAutoUpdate(false))

@ -463,14 +479,14 @@ func TestBridge_ManualUpdate(t *testing.T) {
 			defer done()

 			// Simulate a new version being available, but it's too new for us.
-			mocks.Updater.SetLatestVersion(v2_4_0, v2_4_0)
+			mocks.Updater.SetLatestVersionLegacy(v2_4_0, v2_4_0)

 			// Check for updates.
 			bridge.CheckForUpdates()

 			// We should receive an event indicating an update is available, but we can't install it.
 			require.Equal(t, events.UpdateAvailable{
-				Version: updater.VersionInfo{
+				VersionLegacy: updater.VersionInfoLegacy{
 					Version:           v2_4_0,
 					MinAuto:           v2_4_0,
 					RolloutProportion: 1.0,
@ -484,7 +500,12 @@ func TestBridge_ManualUpdate(t *testing.T) {

 func TestBridge_ForceUpdate(t *testing.T) {
 	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridge.Locator, vaultKey []byte) {
+		unleash.ModifyPollPeriodAndJitter(500*time.Millisecond, 0)
+		s.PushFeatureFlag(unleash.UpdateUseNewVersionFileStructureDisabled)
+
 		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, vaultKey, func(bridge *bridge.Bridge, _ *bridge.Mocks) {
+			// Wait for FF poll.
+			time.Sleep(600 * time.Millisecond)
 			// Get a stream of update events.
 			updateCh, done := bridge.GetEvents(events.UpdateForced{})
 			defer done()
@ -597,7 +618,7 @@ func TestBridge_AddressWithoutKeys(t *testing.T) {
 			require.NoError(t, err)

 			// Create an additional address for the user; it will not have keys.
-			aliasAddrID, err := s.CreateAddress(userID, "alias@pm.me", []byte("password"))
+			aliasAddrID, err := s.CreateAddress(userID, "alias@pm.me", []byte("password"), true)
 			require.NoError(t, err)

 			// Create an API client so we can remove the address keys.
@ -764,7 +785,7 @@ func TestBridge_ChangeAddressOrder(t *testing.T) {
 		require.NoError(t, err)

 		// Create a second address for the user.
-		aliasID, err := s.CreateAddress(userID, "alias@"+s.GetDomain(), password)
+		aliasID, err := s.CreateAddress(userID, "alias@"+s.GetDomain(), password, true)
 		require.NoError(t, err)

 		// Create 10 messages for the user.
--- a/internal/bridge/mocks.go
+++ b/internal/bridge/mocks.go
@ -54,6 +54,9 @@ func NewMocks(tb testing.TB, version, minAuto *semver.Version) *Mocks {
 	mocks.Heartbeat.EXPECT().IsTelemetryAvailable(gomock.Any()).AnyTimes()
 	mocks.Heartbeat.EXPECT().GetHeartbeatPeriodicInterval().AnyTimes().Return(500 * time.Millisecond)

+	// It's called whenever a context is cancelled during sync. We should ought to remove this and make it more granular in the future.
+	mocks.Reporter.EXPECT().ReportMessageWithContext("Failed to sync, will retry later", gomock.Any()).AnyTimes()
+
 	return mocks
 }

@ -119,13 +122,14 @@ func (provider *TestLocationsProvider) UserCache() string {
 }

 type TestUpdater struct {
-	latest updater.VersionInfo
-	lock   sync.RWMutex
+	latest   updater.VersionInfoLegacy
+	releases updater.VersionInfo
+	lock     sync.RWMutex
 }

 func NewTestUpdater(version, minAuto *semver.Version) *TestUpdater {
 	return &TestUpdater{
-		latest: updater.VersionInfo{
+		latest: updater.VersionInfoLegacy{
 			Version: version,
 			MinAuto: minAuto,

@ -134,11 +138,11 @@ func NewTestUpdater(version, minAuto *semver.Version) *TestUpdater {
 	}
 }

-func (testUpdater *TestUpdater) SetLatestVersion(version, minAuto *semver.Version) {
+func (testUpdater *TestUpdater) SetLatestVersionLegacy(version, minAuto *semver.Version) {
 	testUpdater.lock.Lock()
 	defer testUpdater.lock.Unlock()

-	testUpdater.latest = updater.VersionInfo{
+	testUpdater.latest = updater.VersionInfoLegacy{
 		Version: version,
 		MinAuto: minAuto,

@ -146,17 +150,35 @@ func (testUpdater *TestUpdater) SetLatestVersion(version, minAuto *semver.Versio
 	}
 }

-func (testUpdater *TestUpdater) GetVersionInfo(_ context.Context, _ updater.Downloader, _ updater.Channel) (updater.VersionInfo, error) {
+func (testUpdater *TestUpdater) GetVersionInfoLegacy(_ context.Context, _ updater.Downloader, _ updater.Channel) (updater.VersionInfoLegacy, error) {
 	testUpdater.lock.RLock()
 	defer testUpdater.lock.RUnlock()

 	return testUpdater.latest, nil
 }

-func (testUpdater *TestUpdater) InstallUpdate(_ context.Context, _ updater.Downloader, _ updater.VersionInfo) error {
+func (testUpdater *TestUpdater) InstallUpdateLegacy(_ context.Context, _ updater.Downloader, _ updater.VersionInfoLegacy) error {
 	return nil
 }

 func (testUpdater *TestUpdater) RemoveOldUpdates() error {
 	return nil
 }
+
+func (testUpdater *TestUpdater) SetLatestVersion(releases updater.VersionInfo) {
+	testUpdater.lock.Lock()
+	defer testUpdater.lock.Unlock()
+
+	testUpdater.releases = releases
+}
+
+func (testUpdater *TestUpdater) GetVersionInfo(_ context.Context, _ updater.Downloader) (updater.VersionInfo, error) {
+	testUpdater.lock.RLock()
+	defer testUpdater.lock.RUnlock()
+
+	return testUpdater.releases, nil
+}
+
+func (testUpdater *TestUpdater) InstallUpdate(_ context.Context, _ updater.Downloader, _ updater.Release) error {
+	return nil
+}
--- a/internal/bridge/mocks/gluon_mocks.go
+++ b/internal/bridge/mocks/gluon_mocks.go
@ -88,3 +88,18 @@ func (mr *MockReporterMockRecorder) ReportMessageWithContext(arg0, arg1 interfac
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "ReportMessageWithContext", reflect.TypeOf((*MockReporter)(nil).ReportMessageWithContext), arg0, arg1)
 }
+
+
+// ReportWarningWithContext mocks base method.
+func (m *MockReporter) ReportWarningWithContext(arg0 string, arg1 map[string]interface{}) error {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "ReportWarningWithContext", arg0, arg1)
+	ret0, _ := ret[0].(error)
+	return ret0
+}
+
+// ReportWarningWithContext indicates an expected call of ReportWarningWithContext.
+func (mr *MockReporterMockRecorder) ReportWarningWithContext(arg0, arg1 interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "ReportWarningWithContext", reflect.TypeOf((*MockReporter)(nil).ReportMessageWithContext), arg0, arg1)
+}
--- a/internal/bridge/mocks/observability_mocks.go
+++ b/internal/bridge/mocks/observability_mocks.go
@ -25,7 +25,7 @@ func NewMockObservabilitySender(ctrl *gomock.Controller) *MockObservabilitySende

 func (m *MockObservabilitySender) EXPECT() *MockObservabilitySenderRecorder { return m.recorder }

-func (m *MockObservabilitySender) AddDistinctMetrics(errType observability.DistinctionErrorTypeEnum, _ ...proton.ObservabilityMetric) {
+func (m *MockObservabilitySender) AddDistinctMetrics(errType observability.DistinctionMetricTypeEnum, _ ...proton.ObservabilityMetric) {
 	m.ctrl.T.Helper()
 	m.ctrl.Call(m, "AddDistinctMetrics", errType)
 }
@ -35,7 +35,18 @@ func (m *MockObservabilitySender) AddMetrics(metrics ...proton.ObservabilityMetr
 	m.ctrl.Call(m, "AddMetrics", metrics)
 }

-func (mr *MockObservabilitySenderRecorder) AddDistinctMetrics(errType observability.DistinctionErrorTypeEnum, _ ...proton.ObservabilityMetric) *gomock.Call {
+func (m *MockObservabilitySender) AddTimeLimitedMetric(metricType observability.DistinctionMetricTypeEnum, metric proton.ObservabilityMetric) {
+	m.ctrl.T.Helper()
+	m.ctrl.Call(m, "AddTimeLimitedMetric", metricType, metric)
+}
+
+func (m *MockObservabilitySender) GetEmailClient() string {
+	m.ctrl.T.Helper()
+	m.ctrl.Call(m, "GetEmailClient")
+	return ""
+}
+
+func (mr *MockObservabilitySenderRecorder) AddDistinctMetrics(errType observability.DistinctionMetricTypeEnum, _ ...proton.ObservabilityMetric) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock,
 		"AddDistinctMetrics",
@ -47,3 +58,13 @@ func (mr *MockObservabilitySenderRecorder) AddMetrics(metrics ...proton.Observab
 	mr.mock.ctrl.T.Helper()
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "AddMetrics", reflect.TypeOf((*MockObservabilitySender)(nil).AddMetrics), metrics)
 }
+
+func (mr *MockObservabilitySenderRecorder) AddTimeLimitedMetric(metricType observability.DistinctionMetricTypeEnum, metric proton.ObservabilityMetric) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "AddTimeLimitedMetric", reflect.TypeOf((*MockObservabilitySender)(nil).AddTimeLimitedMetric), metricType, metric)
+}
+
+func (mr *MockObservabilitySenderRecorder) GetEmailClient() {
+	mr.mock.ctrl.T.Helper()
+	mr.mock.ctrl.Call(mr.mock, "GetEmailClient", reflect.TypeOf((*MockObservabilitySender)(nil).GetEmailClient))
+}
--- a/internal/bridge/observability_test.go
+++ b/internal/bridge/observability_test.go
@ -127,9 +127,9 @@ func TestBridge_Observability_UserMetric(t *testing.T) {
 	}

 	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridge.Locator, vaultKey []byte) {
-		userMetricPeriod := time.Millisecond * 200
+		userMetricPeriod := time.Millisecond * 600
 		heartbeatPeriod := time.Second * 10
-		throttlePeriod := time.Millisecond * 100
+		throttlePeriod := time.Millisecond * 300
 		observability.ModifyUserMetricInterval(userMetricPeriod)
 		observability.ModifyThrottlePeriod(throttlePeriod)

--- a/internal/bridge/sync_test.go
+++ b/internal/bridge/sync_test.go
@ -355,7 +355,7 @@ func TestBridge_CanProcessEventsDuringSync(t *testing.T) {

 			// Create a new address
 			newAddress := "foo@proton.ch"
-			addrID, err := s.CreateAddress(userID, newAddress, password)
+			addrID, err := s.CreateAddress(userID, newAddress, password, true)
 			require.NoError(t, err)

 			event := <-addressCreatedCh
@ -430,7 +430,7 @@ func TestBridge_EventReplayAfterSyncHasFinished(t *testing.T) {
 			createNumMessages(ctx, t, c, addrID, labelID, numMsg)
 		})

-		addrID1, err := s.CreateAddress(userID, "foo@proton.ch", password)
+		addrID1, err := s.CreateAddress(userID, "foo@proton.ch", password, true)
 		require.NoError(t, err)

 		var allowSyncToProgress atomic.Bool
@ -469,7 +469,7 @@ func TestBridge_EventReplayAfterSyncHasFinished(t *testing.T) {
 			})

 			// User AddrID2 event as a check point to see when the new address was created.
-			addrID2, err := s.CreateAddress(userID, "bar@proton.ch", password)
+			addrID2, err := s.CreateAddress(userID, "bar@proton.ch", password, true)
 			require.NoError(t, err)

 			allowSyncToProgress.Store(true)
@ -552,7 +552,7 @@ func TestBridge_MessageCreateDuringSync(t *testing.T) {
 			})

 			// User AddrID2 event as a check point to see when the new address was created.
-			addrID, err := s.CreateAddress(userID, "bar@proton.ch", password)
+			addrID, err := s.CreateAddress(userID, "bar@proton.ch", password, true)
 			require.NoError(t, err)

 			// At most two events can be published, one for the first address, then for the second.
@ -663,7 +663,7 @@ func TestBridge_AddressOrderChangeDuringSyncInCombinedModeDoesNotTriggerBadEvent
 			require.Equal(t, 1, len(info.Addresses))
 			require.Equal(t, info.Addresses[0], "user@proton.local")

-			addrID2, err := s.CreateAddress(userID, "foo@"+s.GetDomain(), password)
+			addrID2, err := s.CreateAddress(userID, "foo@"+s.GetDomain(), password, true)
 			require.NoError(t, err)

 			require.NoError(t, s.SetAddressOrder(userID, []string{addrID2, addrID}))
--- a/internal/bridge/types.go
+++ b/internal/bridge/types.go
@ -52,7 +52,9 @@ type Autostarter interface {
 }

 type Updater interface {
-	GetVersionInfo(context.Context, updater.Downloader, updater.Channel) (updater.VersionInfo, error)
-	InstallUpdate(context.Context, updater.Downloader, updater.VersionInfo) error
+	GetVersionInfoLegacy(context.Context, updater.Downloader, updater.Channel) (updater.VersionInfoLegacy, error)
+	InstallUpdateLegacy(context.Context, updater.Downloader, updater.VersionInfoLegacy) error
 	RemoveOldUpdates() error
+	GetVersionInfo(context.Context, updater.Downloader) (updater.VersionInfo, error)
+	InstallUpdate(context.Context, updater.Downloader, updater.Release) error
 }
--- a/internal/bridge/updates.go
+++ b/internal/bridge/updates.go
@ -21,22 +21,168 @@ import (
 	"context"
 	"errors"

+	"github.com/Masterminds/semver/v3"
 	"github.com/ProtonMail/gluon/reporter"
 	"github.com/ProtonMail/proton-bridge/v3/internal/events"
 	"github.com/ProtonMail/proton-bridge/v3/internal/safe"
 	"github.com/ProtonMail/proton-bridge/v3/internal/updater"
+	"github.com/elastic/go-sysinfo"
 	"github.com/sirupsen/logrus"
+	"golang.org/x/exp/slices"
 )

 func (bridge *Bridge) CheckForUpdates() {
 	bridge.goUpdate()
 }

-func (bridge *Bridge) InstallUpdate(version updater.VersionInfo) {
-	bridge.installCh <- installJob{version: version, silent: false}
+func (bridge *Bridge) InstallUpdateLegacy(version updater.VersionInfoLegacy) {
+	bridge.installChLegacy <- installJobLegacy{version: version, silent: false}
+}
+
+func (bridge *Bridge) InstallUpdate(release updater.Release) {
+	bridge.installCh <- installJob{Release: release, Silent: false}
 }

 func (bridge *Bridge) handleUpdate(version updater.VersionInfo) {
+	updateChannel := bridge.vault.GetUpdateChannel()
+	updateRollout := bridge.vault.GetUpdateRollout()
+	autoUpdateEnabled := bridge.vault.GetAutoUpdate()
+
+	checkSystemVersion := true
+	hostInfo, err := sysinfo.Host()
+	// If we're unable to get host system information we skip the update's minimum/maximum OS version checks
+	if err != nil {
+		checkSystemVersion = false
+		logrus.WithError(err).Error("Failed to obtain host system info while handling updates")
+		if reporterErr := bridge.reporter.ReportMessageWithContext(
+			"Failed to obtain host system info while handling updates",
+			reporter.Context{"error": err},
+		); reporterErr != nil {
+			logrus.WithError(reporterErr).Error("Failed to report update error")
+		}
+	}
+
+	if len(version.Releases) > 0 {
+		// Update latest is only used to update the release notes and landing page URL
+		bridge.publish(events.UpdateLatest{Release: version.Releases[0]})
+	}
+
+	// minAutoUpdateEvent - used to determine the highest compatible update that satisfies the Minimum Bridge version
+	minAutoUpdateEvent := events.UpdateAvailable{
+		Release:    updater.Release{Version: &semver.Version{}},
+		Compatible: false,
+		Silent:     false,
+	}
+
+	// We assume that the version file is always created in descending order
+	// where newer versions are prepended to the top of the releases
+	// The logic for checking update eligibility is as follows:
+	// 1. Check release channel.
+	// 2. Check whether release version is greater.
+	// 3. Check if rollout is larger.
+	// 4. Check OS Version restrictions (provided that restrictions are provided, and we can extract the OS version).
+	// 5. Check Minimum Compatible Bridge Version.
+	// 6. Check if an update package is provided.
+	// 7. Check auto-update.
+	for _, release := range version.Releases {
+		log := logrus.WithFields(logrus.Fields{
+			"current":               bridge.curVersion,
+			"channel":               updateChannel,
+			"update_version":        release.Version,
+			"update_channel":        release.ReleaseCategory,
+			"update_min_auto":       release.MinAuto,
+			"update_rollout":        release.RolloutProportion,
+			"update_min_os_version": release.SystemVersion.Minimum,
+			"update_max_os_version": release.SystemVersion.Maximum,
+		})
+
+		log.Debug("Checking update release")
+
+		if !release.ReleaseCategory.UpdateEligible(updateChannel) {
+			log.Debug("Update does not satisfy update channel requirement")
+			continue
+		}
+
+		if !release.Version.GreaterThan(bridge.curVersion) {
+			log.Debug("Update version is not greater than current version")
+			continue
+		}
+
+		if release.RolloutProportion < updateRollout {
+			log.Debug("Update has not been rolled out yet")
+			continue
+		}
+
+		if checkSystemVersion {
+			shouldContinue, err := release.SystemVersion.IsHostVersionEligible(log, hostInfo, bridge.getHostVersion)
+			if err != nil && shouldContinue {
+				log.WithError(err).Error(
+					"Failed to verify host system version compatibility during release check." +
+						"Error is non-fatal continuing with checks",
+				)
+			} else if err != nil {
+				log.WithError(err).Error("Failed to verify host system version compatibility during update check")
+				continue
+			}
+
+			if !shouldContinue {
+				log.Debug("Host version does not satisfy system requirements for update")
+				continue
+			}
+		}
+
+		if release.MinAuto != nil && bridge.curVersion.LessThan(release.MinAuto) {
+			log.Debug("Update is available but is incompatible with this Bridge version")
+			if release.Version.GreaterThan(minAutoUpdateEvent.Release.Version) {
+				minAutoUpdateEvent.Release = release
+			}
+			continue
+		}
+
+		// Check if we have a provided installer package
+		if found := slices.IndexFunc(release.File, func(file updater.File) bool {
+			return file.Identifier == updater.PackageIdentifier
+		}); found == -1 {
+			log.Error("Update is available but does not contain update package")
+
+			if reporterErr := bridge.reporter.ReportMessageWithContext(
+				"Available update does not contain update package",
+				reporter.Context{"update_version": release.Version},
+			); reporterErr != nil {
+				log.WithError(reporterErr).Error("Failed to report update error")
+			}
+
+			continue
+		}
+
+		if !autoUpdateEnabled {
+			log.Info("An update is available but auto-update is disabled")
+			bridge.publish(events.UpdateAvailable{
+				Release:    release,
+				Compatible: true,
+				Silent:     false,
+			})
+			return
+		}
+
+		// If we've gotten to this point that means an automatic update is available and we should install it
+		safe.RLock(func() {
+			bridge.installCh <- installJob{Release: release, Silent: true}
+		}, bridge.newVersionLock)
+
+		return
+	}
+
+	// If there's a release with a minAuto requirement that we satisfy (alongside all other checks)
+	// then notify the user that a manual update is needed
+	if !minAutoUpdateEvent.Release.Version.Equal(&semver.Version{}) {
+		bridge.publish(minAutoUpdateEvent)
+	}
+
+	bridge.publish(events.UpdateNotAvailable{})
+}
+
+func (bridge *Bridge) handleUpdateLegacy(version updater.VersionInfoLegacy) {
 	log := logrus.WithFields(logrus.Fields{
 		"version": version.Version,
 		"current": bridge.curVersion,
@ -44,7 +190,7 @@ func (bridge *Bridge) handleUpdate(version updater.VersionInfo) {
 	})

 	bridge.publish(events.UpdateLatest{
-		Version: version,
+		VersionLegacy: version,
 	})

 	switch {
@ -62,33 +208,33 @@ func (bridge *Bridge) handleUpdate(version updater.VersionInfo) {
 		log.Info("An update is available but is incompatible with this version")

 		bridge.publish(events.UpdateAvailable{
-			Version:    version,
-			Compatible: false,
-			Silent:     false,
+			VersionLegacy: version,
+			Compatible:    false,
+			Silent:        false,
 		})

 	case !bridge.vault.GetAutoUpdate():
 		log.Info("An update is available but auto-update is disabled")

 		bridge.publish(events.UpdateAvailable{
-			Version:    version,
-			Compatible: true,
-			Silent:     false,
+			VersionLegacy: version,
+			Compatible:    true,
+			Silent:        false,
 		})

 	default:
 		safe.RLock(func() {
-			bridge.installCh <- installJob{version: version, silent: true}
+			bridge.installChLegacy <- installJobLegacy{version: version, silent: true}
 		}, bridge.newVersionLock)
 	}
 }

-type installJob struct {
-	version updater.VersionInfo
+type installJobLegacy struct {
+	version updater.VersionInfoLegacy
 	silent  bool
 }

-func (bridge *Bridge) installUpdate(ctx context.Context, job installJob) {
+func (bridge *Bridge) installUpdateLegacy(ctx context.Context, job installJobLegacy) {
 	safe.Lock(func() {
 		log := logrus.WithFields(logrus.Fields{
 			"version": job.version.Version,
@ -103,17 +249,12 @@ func (bridge *Bridge) installUpdate(ctx context.Context, job installJob) {
 		log.WithField("silent", job.silent).Info("An update is available")

 		bridge.publish(events.UpdateAvailable{
-			Version:    job.version,
-			Compatible: true,
-			Silent:     job.silent,
+			VersionLegacy: job.version,
+			Compatible:    true,
+			Silent:        job.silent,
 		})

-		bridge.publish(events.UpdateInstalling{
-			Version: job.version,
-			Silent:  job.silent,
-		})
-
-		err := bridge.updater.InstallUpdate(ctx, bridge.api, job.version)
+		err := bridge.updater.InstallUpdateLegacy(ctx, bridge.api, job.version)

 		switch {
 		case errors.Is(err, updater.ErrDownloadVerify):
@ -134,8 +275,79 @@ func (bridge *Bridge) installUpdate(ctx context.Context, job installJob) {
 			log.WithError(err).Error("The update could not be installed")

 			bridge.publish(events.UpdateFailed{
-				Version: job.version,
-				Silent:  job.silent,
+				VersionLegacy: job.version,
+				Silent:        job.silent,
+				Error:         err,
+			})
+
+		default:
+			log.Info("The update was installed successfully")
+
+			bridge.publish(events.UpdateInstalled{
+				VersionLegacy: job.version,
+				Silent:        job.silent,
+			})
+
+			bridge.newVersion = job.version.Version
+		}
+	}, bridge.newVersionLock)
+}
+
+type installJob struct {
+	Release updater.Release
+	Silent  bool
+}
+
+func (bridge *Bridge) installUpdate(ctx context.Context, job installJob) {
+	safe.Lock(func() {
+		log := logrus.WithFields(logrus.Fields{
+			"version": job.Release.Version,
+			"current": bridge.curVersion,
+			"channel": bridge.vault.GetUpdateChannel(),
+		})
+
+		if !job.Release.Version.GreaterThan(bridge.newVersion) {
+			return
+		}
+
+		log.WithField("silent", job.Silent).Info("An update is available")
+
+		bridge.publish(events.UpdateAvailable{
+			Release:    job.Release,
+			Compatible: true,
+			Silent:     job.Silent,
+		})
+
+		err := bridge.updater.InstallUpdate(ctx, bridge.api, job.Release)
+		switch {
+		case errors.Is(err, updater.ErrReleaseUpdatePackageMissing):
+			log.WithError(err).Error("The update could not be installed but we will fail silently")
+			if reporterErr := bridge.reporter.ReportExceptionWithContext(
+				"Cannot download update, update package is missing",
+				reporter.Context{"error": err},
+			); reporterErr != nil {
+				log.WithError(reporterErr).Error("Failed to report update error")
+			}
+		case errors.Is(err, updater.ErrDownloadVerify):
+			// BRIDGE-207: if download or verification fails, we do not want to trigger a manual update. We report in the log and to Sentry
+			// and we fail silently.
+			log.WithError(err).Error("The update could not be installed, but we will fail silently")
+			if reporterErr := bridge.reporter.ReportMessageWithContext(
+				"Cannot download or verify update",
+				reporter.Context{"error": err},
+			); reporterErr != nil {
+				log.WithError(reporterErr).Error("Failed to report update error")
+			}
+
+		case errors.Is(err, updater.ErrUpdateAlreadyInstalled):
+			log.Info("The update was already installed")
+
+		case err != nil:
+			log.WithError(err).Error("The update could not be installed")
+
+			bridge.publish(events.UpdateFailed{
+				Release: job.Release,
+				Silent:  job.Silent,
 				Error:   err,
 			})

@ -143,11 +355,11 @@ func (bridge *Bridge) installUpdate(ctx context.Context, job installJob) {
 			log.Info("The update was installed successfully")

 			bridge.publish(events.UpdateInstalled{
-				Version: job.version,
-				Silent:  job.silent,
+				Release: job.Release,
+				Silent:  job.Silent,
 			})

-			bridge.newVersion = job.version.Version
+			bridge.newVersion = job.Release.Version
 		}
 	}, bridge.newVersionLock)
 }
--- a/internal/bridge/updates_test.go
+++ b/internal/bridge/updates_test.go
@ -0,0 +1,700 @@
+// Copyright (c) 2025 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
+
+package bridge_test
+
+import (
+	"context"
+	"runtime"
+	"testing"
+	"time"
+
+	"github.com/Masterminds/semver/v3"
+	"github.com/ProtonMail/go-proton-api"
+	"github.com/ProtonMail/go-proton-api/server"
+	bridgePkg "github.com/ProtonMail/proton-bridge/v3/internal/bridge"
+	"github.com/ProtonMail/proton-bridge/v3/internal/events"
+	"github.com/ProtonMail/proton-bridge/v3/internal/updater"
+	"github.com/ProtonMail/proton-bridge/v3/internal/updater/versioncompare"
+	"github.com/elastic/go-sysinfo/types"
+	"github.com/stretchr/testify/require"
+)
+
+// NOTE: we always assume the highest version is always the first in the release json array
+
+func Test_Update_BetaEligible(t *testing.T) {
+	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridgePkg.Locator, vaultKey []byte) {
+		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, vaultKey, func(bridge *bridgePkg.Bridge, mocks *bridgePkg.Mocks) {
+			updateCh, done := bridge.GetEvents(events.UpdateInstalled{})
+			defer done()
+
+			err := bridge.SetUpdateChannel(updater.EarlyChannel)
+			require.NoError(t, err)
+
+			bridge.SetCurrentVersionTest(semver.MustParse("2.1.1"))
+
+			expectedRelease := updater.Release{
+				ReleaseCategory:   updater.EarlyAccessReleaseCategory,
+				Version:           semver.MustParse("2.1.2"),
+				SystemVersion:     versioncompare.SystemVersion{},
+				RolloutProportion: 1.0,
+				MinAuto:           &semver.Version{},
+				File: []updater.File{
+					{
+						URL:        "RANDOM_INSTALLER_URL",
+						Identifier: updater.InstallerIdentifier,
+					},
+					{
+						URL:        "RANDOM_PACKAGE_URL",
+						Identifier: updater.PackageIdentifier,
+					},
+				},
+			}
+
+			updaterData := updater.VersionInfo{Releases: []updater.Release{
+				expectedRelease,
+			}}
+
+			go func() {
+				time.Sleep(1 * time.Second)
+				mocks.Updater.SetLatestVersion(updaterData)
+				bridge.CheckForUpdates()
+			}()
+
+			select {
+			case update := <-updateCh:
+				require.Equal(t, events.UpdateInstalled{
+					Release: expectedRelease,
+					Silent:  true,
+				}, update)
+			case <-time.After(2 * time.Second):
+				t.Fatal("timeout waiting for update")
+			}
+		})
+	})
+}
+
+func Test_Update_Stable(t *testing.T) {
+	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridgePkg.Locator, vaultKey []byte) {
+		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, vaultKey, func(bridge *bridgePkg.Bridge, mocks *bridgePkg.Mocks) {
+			updateCh, done := bridge.GetEvents(events.UpdateInstalled{})
+			defer done()
+
+			err := bridge.SetUpdateChannel(updater.StableChannel)
+			require.NoError(t, err)
+
+			bridge.SetCurrentVersionTest(semver.MustParse("2.1.1"))
+
+			expectedRelease := updater.Release{
+				ReleaseCategory:   updater.StableReleaseCategory,
+				Version:           semver.MustParse("2.1.3"),
+				SystemVersion:     versioncompare.SystemVersion{},
+				RolloutProportion: 1.0,
+				MinAuto:           &semver.Version{},
+				File: []updater.File{
+					{
+						URL:        "RANDOM_INSTALLER_URL",
+						Identifier: updater.InstallerIdentifier,
+					},
+					{
+						URL:        "RANDOM_PACKAGE_URL",
+						Identifier: updater.PackageIdentifier,
+					},
+				},
+			}
+
+			updaterData := updater.VersionInfo{Releases: []updater.Release{
+				{
+					ReleaseCategory:   updater.EarlyAccessReleaseCategory,
+					Version:           semver.MustParse("2.1.4"),
+					SystemVersion:     versioncompare.SystemVersion{},
+					RolloutProportion: 1.0,
+					MinAuto:           &semver.Version{},
+					File: []updater.File{
+						{
+							URL:        "RANDOM_INSTALLER_URL",
+							Identifier: updater.InstallerIdentifier,
+						},
+						{
+							URL:        "RANDOM_PACKAGE_URL",
+							Identifier: updater.PackageIdentifier,
+						},
+					},
+				},
+				expectedRelease,
+			}}
+
+			mocks.Updater.SetLatestVersion(updaterData)
+
+			bridge.CheckForUpdates()
+
+			require.Equal(t, events.UpdateInstalled{
+				Release: expectedRelease,
+				Silent:  true,
+			}, <-updateCh)
+		})
+	})
+}
+
+func Test_Update_CurrentReleaseNewest(t *testing.T) {
+	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridgePkg.Locator, vaultKey []byte) {
+		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, vaultKey, func(bridge *bridgePkg.Bridge, mocks *bridgePkg.Mocks) {
+			updateCh, done := bridge.GetEvents(events.UpdateNotAvailable{})
+			defer done()
+
+			err := bridge.SetUpdateChannel(updater.StableChannel)
+			require.NoError(t, err)
+
+			bridge.SetCurrentVersionTest(semver.MustParse("2.1.5"))
+
+			expectedRelease := updater.Release{
+				ReleaseCategory:   updater.StableReleaseCategory,
+				Version:           semver.MustParse("2.1.3"),
+				SystemVersion:     versioncompare.SystemVersion{},
+				RolloutProportion: 1.0,
+				MinAuto:           &semver.Version{},
+				File: []updater.File{
+					{
+						URL:        "RANDOM_INSTALLER_URL",
+						Identifier: updater.InstallerIdentifier,
+					},
+					{
+						URL:        "RANDOM_PACKAGE_URL",
+						Identifier: updater.PackageIdentifier,
+					},
+				},
+			}
+
+			updaterData := updater.VersionInfo{Releases: []updater.Release{
+				{
+					ReleaseCategory:   updater.EarlyAccessReleaseCategory,
+					Version:           semver.MustParse("2.1.4"),
+					SystemVersion:     versioncompare.SystemVersion{},
+					RolloutProportion: 1.0,
+					MinAuto:           &semver.Version{},
+					File: []updater.File{
+						{
+							URL:        "RANDOM_INSTALLER_URL",
+							Identifier: updater.InstallerIdentifier,
+						},
+						{
+							URL:        "RANDOM_PACKAGE_URL",
+							Identifier: updater.PackageIdentifier,
+						},
+					},
+				},
+				expectedRelease,
+			}}
+
+			mocks.Updater.SetLatestVersion(updaterData)
+			bridge.CheckForUpdates()
+
+			require.Equal(t, events.UpdateNotAvailable{}, <-updateCh)
+		})
+	})
+}
+
+func Test_Update_NotRolledOutYet(t *testing.T) {
+	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridgePkg.Locator, vaultKey []byte) {
+		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, vaultKey, func(bridge *bridgePkg.Bridge, mocks *bridgePkg.Mocks) {
+			require.NoError(t, bridge.SetUpdateChannel(updater.EarlyChannel))
+			bridge.SetCurrentVersionTest(semver.MustParse("2.0.0"))
+			require.NoError(t, bridge.SetRolloutPercentageTest(1.0))
+
+			updaterData := updater.VersionInfo{Releases: []updater.Release{
+				{
+					ReleaseCategory:   updater.StableReleaseCategory,
+					Version:           semver.MustParse("2.1.5"),
+					SystemVersion:     versioncompare.SystemVersion{},
+					RolloutProportion: 0.5,
+					MinAuto:           &semver.Version{},
+					File: []updater.File{
+						{
+							URL:        "RANDOM_INSTALLER_URL",
+							Identifier: updater.InstallerIdentifier,
+						},
+						{
+							URL:        "RANDOM_PACKAGE_URL",
+							Identifier: updater.PackageIdentifier,
+						},
+					},
+				},
+				{
+					ReleaseCategory:   updater.StableReleaseCategory,
+					Version:           semver.MustParse("2.1.4"),
+					SystemVersion:     versioncompare.SystemVersion{},
+					RolloutProportion: 0.5,
+					MinAuto:           &semver.Version{},
+					File: []updater.File{
+						{
+							URL:        "RANDOM_INSTALLER_URL",
+							Identifier: updater.InstallerIdentifier,
+						},
+						{
+							URL:        "RANDOM_PACKAGE_URL",
+							Identifier: updater.PackageIdentifier,
+						},
+					},
+				},
+			}}
+
+			mocks.Updater.SetLatestVersion(updaterData)
+
+			updateCh, done := bridge.GetEvents(events.UpdateNotAvailable{})
+			defer done()
+
+			bridge.CheckForUpdates()
+
+			require.Equal(t, events.UpdateNotAvailable{}, <-updateCh)
+		})
+	})
+}
+
+func Test_Update_CheckOSVersion_NoUpdate(t *testing.T) {
+	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridgePkg.Locator, vaultKey []byte) {
+		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, vaultKey, func(bridge *bridgePkg.Bridge, mocks *bridgePkg.Mocks) {
+			require.NoError(t, bridge.SetAutoUpdate(true))
+			require.NoError(t, bridge.SetUpdateChannel(updater.StableChannel))
+
+			currentBridgeVersion := semver.MustParse("2.1.5")
+			bridge.SetCurrentVersionTest(currentBridgeVersion)
+
+			// Override the OS version check
+			bridge.SetHostVersionGetterTest(func(_ types.Host) string {
+				return "10.0.0"
+			})
+
+			updateNotAvailableCh, done := bridge.GetEvents(events.UpdateNotAvailable{})
+			defer done()
+
+			updateCh, updateChDone := bridge.GetEvents(events.UpdateInstalled{})
+			defer updateChDone()
+
+			expectedRelease := updater.Release{
+				ReleaseCategory: updater.StableReleaseCategory,
+				Version:         semver.MustParse("2.4.0"),
+				SystemVersion: versioncompare.SystemVersion{
+					Minimum: "12.0.0",
+					Maximum: "13.0.0",
+				},
+				RolloutProportion: 1.0,
+				File: []updater.File{
+					{
+						URL:        "RANDOM_INSTALLER_URL",
+						Identifier: updater.InstallerIdentifier,
+					},
+					{
+						URL:        "RANDOM_PACKAGE_URL",
+						Identifier: updater.PackageIdentifier,
+					},
+				},
+			}
+
+			updaterData := updater.VersionInfo{Releases: []updater.Release{
+				expectedRelease,
+				{
+					ReleaseCategory: updater.StableReleaseCategory,
+					Version:         semver.MustParse("2.3.0"),
+					SystemVersion: versioncompare.SystemVersion{
+						Minimum: "10.1.0",
+						Maximum: "11.5",
+					},
+					RolloutProportion: 1.0,
+					File: []updater.File{
+						{
+							URL:        "RANDOM_INSTALLER_URL",
+							Identifier: updater.InstallerIdentifier,
+						},
+						{
+							URL:        "RANDOM_PACKAGE_URL",
+							Identifier: updater.PackageIdentifier,
+						},
+					},
+				},
+			}}
+
+			mocks.Updater.SetLatestVersion(updaterData)
+
+			bridge.CheckForUpdates()
+
+			if runtime.GOOS == "darwin" {
+				require.Equal(t, events.UpdateNotAvailable{}, <-updateNotAvailableCh)
+			} else {
+				require.Equal(t, events.UpdateInstalled{
+					Release: expectedRelease,
+					Silent:  true,
+				}, <-updateCh)
+			}
+		})
+	})
+}
+
+func Test_Update_CheckOSVersion_HasUpdate(t *testing.T) {
+	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridgePkg.Locator, vaultKey []byte) {
+		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, vaultKey, func(bridge *bridgePkg.Bridge, mocks *bridgePkg.Mocks) {
+			require.NoError(t, bridge.SetAutoUpdate(true))
+			require.NoError(t, bridge.SetUpdateChannel(updater.StableChannel))
+
+			updateCh, done := bridge.GetEvents(events.UpdateInstalled{})
+			defer done()
+
+			currentBridgeVersion := semver.MustParse("2.1.5")
+			bridge.SetCurrentVersionTest(currentBridgeVersion)
+
+			// Override the OS version check
+			bridge.SetHostVersionGetterTest(func(_ types.Host) string {
+				return "10.0.0"
+			})
+
+			expectedUpdateRelease := updater.Release{
+				ReleaseCategory: updater.StableReleaseCategory,
+				Version:         semver.MustParse("2.2.0"),
+				SystemVersion: versioncompare.SystemVersion{
+					Minimum: "10.0.0",
+					Maximum: "10.1.12",
+				},
+				RolloutProportion: 1.0,
+				File: []updater.File{
+					{
+						URL:        "RANDOM_INSTALLER_URL",
+						Identifier: updater.InstallerIdentifier,
+					},
+					{
+						URL:        "RANDOM_PACKAGE_URL",
+						Identifier: updater.PackageIdentifier,
+					},
+				},
+			}
+
+			expectedUpdateReleaseWindowsLinux := updater.Release{
+				ReleaseCategory: updater.StableReleaseCategory,
+				Version:         semver.MustParse("2.4.0"),
+				SystemVersion: versioncompare.SystemVersion{
+					Minimum: "12.0.0",
+				},
+				RolloutProportion: 1.0,
+				File: []updater.File{
+					{
+						URL:        "RANDOM_INSTALLER_URL",
+						Identifier: updater.InstallerIdentifier,
+					},
+					{
+						URL:        "RANDOM_PACKAGE_URL",
+						Identifier: updater.PackageIdentifier,
+					},
+				},
+			}
+
+			updaterData := updater.VersionInfo{Releases: []updater.Release{
+				expectedUpdateReleaseWindowsLinux,
+				{
+					ReleaseCategory: updater.StableReleaseCategory,
+					Version:         semver.MustParse("2.3.0"),
+					SystemVersion: versioncompare.SystemVersion{
+						Minimum: "11.0.0",
+					},
+					RolloutProportion: 1.0,
+					File: []updater.File{
+						{
+							URL:        "RANDOM_INSTALLER_URL",
+							Identifier: updater.InstallerIdentifier,
+						},
+						{
+							URL:        "RANDOM_PACKAGE_URL",
+							Identifier: updater.PackageIdentifier,
+						},
+					},
+				},
+				expectedUpdateRelease,
+				{
+					ReleaseCategory:   updater.StableReleaseCategory,
+					Version:           semver.MustParse("2.1.0"),
+					SystemVersion:     versioncompare.SystemVersion{},
+					RolloutProportion: 1.0,
+					File: []updater.File{
+						{
+							URL:        "RANDOM_INSTALLER_URL",
+							Identifier: updater.InstallerIdentifier,
+						},
+						{
+							URL:        "RANDOM_PACKAGE_URL",
+							Identifier: updater.PackageIdentifier,
+						},
+					},
+				},
+			}}
+
+			mocks.Updater.SetLatestVersion(updaterData)
+
+			bridge.CheckForUpdates()
+
+			if runtime.GOOS == "darwin" {
+				require.Equal(t, events.UpdateInstalled{
+					Release: expectedUpdateRelease,
+					Silent:  true,
+				}, <-updateCh)
+			} else {
+				require.Equal(t, events.UpdateInstalled{
+					Release: expectedUpdateReleaseWindowsLinux,
+					Silent:  true,
+				}, <-updateCh)
+			}
+		})
+	})
+}
+
+func Test_Update_UpdateFromMinVer_UpdateAvailable(t *testing.T) {
+	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridgePkg.Locator, vaultKey []byte) {
+		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, vaultKey, func(bridge *bridgePkg.Bridge, mocks *bridgePkg.Mocks) {
+			require.NoError(t, bridge.SetAutoUpdate(true))
+			require.NoError(t, bridge.SetUpdateChannel(updater.StableChannel))
+
+			currentBridgeVersion := semver.MustParse("2.1.5")
+			bridge.SetCurrentVersionTest(currentBridgeVersion)
+
+			updateCh, done := bridge.GetEvents(events.UpdateInstalled{})
+			defer done()
+
+			expectedUpdateRelease := updater.Release{
+				ReleaseCategory:   updater.StableReleaseCategory,
+				Version:           semver.MustParse("2.2.0"),
+				SystemVersion:     versioncompare.SystemVersion{},
+				RolloutProportion: 1.0,
+				MinAuto:           currentBridgeVersion,
+				File: []updater.File{
+					{
+						URL:        "RANDOM_INSTALLER_URL",
+						Identifier: updater.InstallerIdentifier,
+					},
+					{
+						URL:        "RANDOM_PACKAGE_URL",
+						Identifier: updater.PackageIdentifier,
+					},
+				},
+			}
+
+			updaterData := updater.VersionInfo{Releases: []updater.Release{
+				{
+					ReleaseCategory:   updater.StableReleaseCategory,
+					Version:           semver.MustParse("2.3.0"),
+					SystemVersion:     versioncompare.SystemVersion{},
+					RolloutProportion: 1.0,
+					MinAuto:           semver.MustParse("2.2.1"),
+					File: []updater.File{
+						{
+							URL:        "RANDOM_INSTALLER_URL",
+							Identifier: updater.InstallerIdentifier,
+						},
+						{
+							URL:        "RANDOM_PACKAGE_URL",
+							Identifier: updater.PackageIdentifier,
+						},
+					},
+				},
+				{
+					ReleaseCategory:   updater.StableReleaseCategory,
+					Version:           semver.MustParse("2.2.1"),
+					SystemVersion:     versioncompare.SystemVersion{},
+					RolloutProportion: 1.0,
+					MinAuto:           semver.MustParse("2.2.0"),
+					File: []updater.File{
+						{
+							URL:        "RANDOM_INSTALLER_URL",
+							Identifier: updater.InstallerIdentifier,
+						},
+						{
+							URL:        "RANDOM_PACKAGE_URL",
+							Identifier: updater.PackageIdentifier,
+						},
+					},
+				},
+				expectedUpdateRelease,
+			}}
+
+			mocks.Updater.SetLatestVersion(updaterData)
+
+			bridge.CheckForUpdates()
+
+			require.Equal(t, events.UpdateInstalled{
+				Release: expectedUpdateRelease,
+				Silent:  true,
+			}, <-updateCh)
+		})
+	})
+}
+
+// Test_Update_UpdateFromMinVer_NoCompatibleVersionForceManual -
+// if we have an update, but we don't satisfy minVersion, a manual update to the highest possible version should be performed.
+func Test_Update_UpdateFromMinVer_NoCompatibleVersionForceManual(t *testing.T) {
+	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridgePkg.Locator, vaultKey []byte) {
+		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, vaultKey, func(bridge *bridgePkg.Bridge, mocks *bridgePkg.Mocks) {
+			require.NoError(t, bridge.SetAutoUpdate(true))
+			require.NoError(t, bridge.SetUpdateChannel(updater.StableChannel))
+
+			currentBridgeVersion := semver.MustParse("2.1.5")
+			bridge.SetCurrentVersionTest(currentBridgeVersion)
+
+			updateCh, done := bridge.GetEvents(events.UpdateAvailable{})
+			defer done()
+
+			expectedUpdateRelease := updater.Release{
+				ReleaseCategory:   updater.StableReleaseCategory,
+				Version:           semver.MustParse("2.3.0"),
+				SystemVersion:     versioncompare.SystemVersion{},
+				RolloutProportion: 1.0,
+				MinAuto:           semver.MustParse("2.2.1"),
+				File: []updater.File{
+					{
+						URL:        "RANDOM_INSTALLER_URL",
+						Identifier: updater.InstallerIdentifier,
+					},
+					{
+						URL:        "RANDOM_PACKAGE_URL",
+						Identifier: updater.PackageIdentifier,
+					},
+				},
+			}
+
+			updaterData := updater.VersionInfo{Releases: []updater.Release{
+				{
+					ReleaseCategory:   updater.StableReleaseCategory,
+					Version:           semver.MustParse("2.2.1"),
+					SystemVersion:     versioncompare.SystemVersion{},
+					RolloutProportion: 1.0,
+					MinAuto:           semver.MustParse("2.2.0"),
+					File: []updater.File{
+						{
+							URL:        "RANDOM_INSTALLER_URL",
+							Identifier: updater.InstallerIdentifier,
+						},
+						{
+							URL:        "RANDOM_PACKAGE_URL",
+							Identifier: updater.PackageIdentifier,
+						},
+					},
+				},
+				{
+					ReleaseCategory:   updater.StableReleaseCategory,
+					Version:           semver.MustParse("2.2.0"),
+					SystemVersion:     versioncompare.SystemVersion{},
+					RolloutProportion: 1.0,
+					MinAuto:           semver.MustParse("2.1.6"),
+					File: []updater.File{
+						{
+							URL:        "RANDOM_INSTALLER_URL",
+							Identifier: updater.InstallerIdentifier,
+						},
+						{
+							URL:        "RANDOM_PACKAGE_URL",
+							Identifier: updater.PackageIdentifier,
+						},
+					},
+				},
+				expectedUpdateRelease,
+			}}
+
+			mocks.Updater.SetLatestVersion(updaterData)
+
+			bridge.CheckForUpdates()
+
+			require.Equal(t, events.UpdateAvailable{
+				Release:    expectedUpdateRelease,
+				Silent:     false,
+				Compatible: false,
+			}, <-updateCh)
+		})
+	})
+}
+
+// Test_Update_UpdateFromMinVer_NoCompatibleVersionForceManual_BetaMismatch - only Beta updates are available
+// nor do we satisfy the minVersion, we can't do anything in this case.
+func Test_Update_UpdateFromMinVer_NoCompatibleVersionForceManual_BetaMismatch(t *testing.T) {
+	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridgePkg.Locator, vaultKey []byte) {
+		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, vaultKey, func(bridge *bridgePkg.Bridge, mocks *bridgePkg.Mocks) {
+			require.NoError(t, bridge.SetAutoUpdate(true))
+			require.NoError(t, bridge.SetUpdateChannel(updater.StableChannel))
+
+			currentBridgeVersion := semver.MustParse("2.1.5")
+			bridge.SetCurrentVersionTest(currentBridgeVersion)
+
+			updateCh, done := bridge.GetEvents(events.UpdateNotAvailable{})
+			defer done()
+
+			expectedUpdateRelease := updater.Release{
+				ReleaseCategory:   updater.EarlyAccessReleaseCategory,
+				Version:           semver.MustParse("2.3.0"),
+				SystemVersion:     versioncompare.SystemVersion{},
+				RolloutProportion: 1.0,
+				MinAuto:           semver.MustParse("2.2.1"),
+				File: []updater.File{
+					{
+						URL:        "RANDOM_INSTALLER_URL",
+						Identifier: updater.InstallerIdentifier,
+					},
+					{
+						URL:        "RANDOM_PACKAGE_URL",
+						Identifier: updater.PackageIdentifier,
+					},
+				},
+			}
+
+			updaterData := updater.VersionInfo{Releases: []updater.Release{
+				{
+					ReleaseCategory:   updater.EarlyAccessReleaseCategory,
+					Version:           semver.MustParse("2.2.1"),
+					SystemVersion:     versioncompare.SystemVersion{},
+					RolloutProportion: 1.0,
+					MinAuto:           semver.MustParse("2.2.0"),
+					File: []updater.File{
+						{
+							URL:        "RANDOM_INSTALLER_URL",
+							Identifier: updater.InstallerIdentifier,
+						},
+						{
+							URL:        "RANDOM_PACKAGE_URL",
+							Identifier: updater.PackageIdentifier,
+						},
+					},
+				},
+				{
+					ReleaseCategory:   updater.EarlyAccessReleaseCategory,
+					Version:           semver.MustParse("2.2.0"),
+					SystemVersion:     versioncompare.SystemVersion{},
+					RolloutProportion: 1.0,
+					MinAuto:           semver.MustParse("2.1.6"),
+					File: []updater.File{
+						{
+							URL:        "RANDOM_INSTALLER_URL",
+							Identifier: updater.InstallerIdentifier,
+						},
+						{
+							URL:        "RANDOM_PACKAGE_URL",
+							Identifier: updater.PackageIdentifier,
+						},
+					},
+				},
+				expectedUpdateRelease,
+			}}
+
+			mocks.Updater.SetLatestVersion(updaterData)
+
+			bridge.CheckForUpdates()
+
+			require.Equal(t, events.UpdateNotAvailable{}, <-updateCh)
+		})
+	})
+}
--- a/internal/bridge/user.go
+++ b/internal/bridge/user.go
@ -551,7 +551,7 @@ func (bridge *Bridge) addUserWithVault(
 		syncSettingsPath,
 		isNew,
 		bridge.notificationStore,
-		bridge.unleashService.GetFlagValue,
+		bridge.unleashService,
 	)
 	if err != nil {
 		return fmt.Errorf("failed to create user: %w", err)
--- a/internal/bridge/user_event_test.go
+++ b/internal/bridge/user_event_test.go
@ -23,6 +23,7 @@ import (
 	"net"
 	"net/http"
 	"net/mail"
+	"runtime"
 	"strings"
 	"sync/atomic"
 	"testing"
@ -76,6 +77,9 @@ func TestBridge_User_RefreshEvent(t *testing.T) {
 		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, storeKey, func(bridge *bridge.Bridge, _ *bridge.Mocks) {
 			syncCh, closeCh := chToType[events.Event, events.SyncFinished](bridge.GetEvents(events.SyncFinished{}))

+			if runtime.GOOS != "windows" {
+				require.Equal(t, userID, (<-syncCh).UserID)
+			}
 			require.Equal(t, userID, (<-syncCh).UserID)
 			closeCh()

@ -304,7 +308,7 @@ func TestBridge_User_AddressEvents_NoBadEvent(t *testing.T) {
 		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, storeKey, func(bridge *bridge.Bridge, _ *bridge.Mocks) {
 			userLoginAndSync(ctx, t, bridge, "user", password)

-			addrID, err = s.CreateAddress(userID, "other@pm.me", password)
+			addrID, err = s.CreateAddress(userID, "other@pm.me", password, true)
 			require.NoError(t, err)
 			userContinueEventProcess(ctx, t, s, bridge)

@ -312,7 +316,7 @@ func TestBridge_User_AddressEvents_NoBadEvent(t *testing.T) {
 			userContinueEventProcess(ctx, t, s, bridge)
 		})

-		otherID, err := s.CreateAddress(userID, "another@pm.me", password)
+		otherID, err := s.CreateAddress(userID, "another@pm.me", password, true)
 		require.NoError(t, err)
 		require.NoError(t, s.RemoveAddress(userID, otherID))

@ -328,6 +332,87 @@ func TestBridge_User_AddressEvents_NoBadEvent(t *testing.T) {
 	})
 }

+func TestBridge_User_AddressEvents_BYOEAddressAdded(t *testing.T) {
+	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridge.Locator, storeKey []byte) {
+		// Create a user.
+		userID, addrID, err := s.CreateUser("user", password)
+		require.NoError(t, err)
+
+		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, storeKey, func(bridge *bridge.Bridge, _ *bridge.Mocks) {
+			userLoginAndSync(ctx, t, bridge, "user", password)
+
+			// Create an additional proton address
+			addrID, err = s.CreateAddress(userID, "other@pm.me", password, true)
+			require.NoError(t, err)
+			userContinueEventProcess(ctx, t, s, bridge)
+			require.NoError(t, s.AddAddressCreatedEvent(userID, addrID))
+			userContinueEventProcess(ctx, t, s, bridge)
+
+			userInfo, err := bridge.GetUserInfo(userID)
+			require.NoError(t, err)
+			require.Equal(t, 2, len(userInfo.Addresses))
+
+			// Create an external address with sending disabled.
+			externalID, err := s.CreateExternalAddress(userID, "another@yahoo.com", password, false)
+			require.NoError(t, err)
+			userContinueEventProcess(ctx, t, s, bridge)
+			require.NoError(t, s.AddAddressCreatedEvent(userID, externalID))
+			userContinueEventProcess(ctx, t, s, bridge)
+
+			// User addresses should still return 2, as we ignore the external address.
+			userInfo, err = bridge.GetUserInfo(userID)
+			require.NoError(t, err)
+			require.Equal(t, 2, len(userInfo.Addresses))
+
+			// Create an external address w. sending enabled. This is considered a BYOE address.
+			BYOEAddrID, err := s.CreateExternalAddress(userID, "other@yahoo.com", password, true)
+			require.NoError(t, err)
+			userContinueEventProcess(ctx, t, s, bridge)
+			require.NoError(t, s.AddAddressCreatedEvent(userID, BYOEAddrID))
+			userContinueEventProcess(ctx, t, s, bridge)
+
+			userInfo, err = bridge.GetUserInfo(userID)
+			require.NoError(t, err)
+			require.Equal(t, 3, len(userInfo.Addresses))
+		})
+	})
+}
+
+func TestBridge_User_AddressEvents_ExternalAddressSendChanged(t *testing.T) {
+	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridge.Locator, storeKey []byte) {
+		userID, _, err := s.CreateUser("user", password)
+		require.NoError(t, err)
+
+		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, storeKey, func(bridge *bridge.Bridge, _ *bridge.Mocks) {
+			userLoginAndSync(ctx, t, bridge, "user", password)
+
+			// Create an additional external address.
+			externalID, err := s.CreateExternalAddress(userID, "other@yahoo.me", password, false)
+			require.NoError(t, err)
+			userContinueEventProcess(ctx, t, s, bridge)
+			require.NoError(t, s.AddAddressCreatedEvent(userID, externalID))
+			userContinueEventProcess(ctx, t, s, bridge)
+
+			// We expect only one address, the external one without sending should not be considered a valid address.
+			userInfo, err := bridge.GetUserInfo(userID)
+			require.NoError(t, err)
+			require.Equal(t, 1, len(userInfo.Addresses))
+
+			// Change it to allow sending such that it becomes a BYOE address.
+			err = s.ChangeAddressAllowSend(userID, externalID, true)
+			require.NoError(t, err)
+			userContinueEventProcess(ctx, t, s, bridge)
+			require.NoError(t, s.AddAddressUpdatedEvent(userID, externalID))
+			userContinueEventProcess(ctx, t, s, bridge)
+
+			// We should now have 2 usable addresses listed.
+			userInfo, err = bridge.GetUserInfo(userID)
+			require.NoError(t, err)
+			require.Equal(t, 2, len(userInfo.Addresses))
+		})
+	})
+}
+
 func TestBridge_User_AddressEventUpdatedForAddressThatDoesNotExist_NoBadEvent(t *testing.T) {
 	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridge.Locator, storeKey []byte) {
 		// Create a user.
@ -694,7 +779,7 @@ func TestBridge_User_DisableEnableAddress(t *testing.T) {
 		require.NoError(t, err)

 		// Create an additional address for the user.
-		aliasID, err := s.CreateAddress(userID, "alias@"+s.GetDomain(), password)
+		aliasID, err := s.CreateAddress(userID, "alias@"+s.GetDomain(), password, true)
 		require.NoError(t, err)

 		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, storeKey, func(bridge *bridge.Bridge, _ *bridge.Mocks) {
@ -745,7 +830,7 @@ func TestBridge_User_CreateDisabledAddress(t *testing.T) {
 		require.NoError(t, err)

 		// Create an additional address for the user.
-		aliasID, err := s.CreateAddress(userID, "alias@"+s.GetDomain(), password)
+		aliasID, err := s.CreateAddress(userID, "alias@"+s.GetDomain(), password, true)
 		require.NoError(t, err)

 		// Immediately disable the address.
--- a/internal/bridge/user_test.go
+++ b/internal/bridge/user_test.go
@ -658,7 +658,7 @@ func TestBridge_UserInfo_Alias(t *testing.T) {
 			require.NoError(t, err)

 			// Give the new user an alias.
-			require.NoError(t, getErr(s.CreateAddress(userID, "alias@pm.me", []byte("password"))))
+			require.NoError(t, getErr(s.CreateAddress(userID, "alias@pm.me", []byte("password"), true)))

 			// Login the user.
 			require.NoError(t, getErr(bridge.LoginFull(ctx, "primary", []byte("password"), nil, nil)))
@ -706,7 +706,7 @@ func TestBridge_User_GetAddresses(t *testing.T) {
 		// Create a user.
 		userID, _, err := s.CreateUser("user", password)
 		require.NoError(t, err)
-		addrID2, err := s.CreateAddress(userID, "user@external.com", []byte("password"))
+		addrID2, err := s.CreateAddress(userID, "user@external.com", password, false)
 		require.NoError(t, err)
 		require.NoError(t, s.ChangeAddressType(userID, addrID2, proton.AddressTypeExternal))

@ -720,6 +720,29 @@ func TestBridge_User_GetAddresses(t *testing.T) {
 	})
 }

+func TestBridge_User_GetAddresses_BYOE(t *testing.T) {
+	withEnv(t, func(ctx context.Context, s *server.Server, netCtl *proton.NetCtl, locator bridge.Locator, storeKey []byte) {
+		// Create a user.
+		userID, _, err := s.CreateUser("user", password)
+		require.NoError(t, err)
+		// Add a non-sending external address.
+		_, err = s.CreateExternalAddress(userID, "user@external.com", password, false)
+		require.NoError(t, err)
+		// Add a BYOE address.
+		_, err = s.CreateExternalAddress(userID, "user2@external.com", password, true)
+		require.NoError(t, err)
+
+		withBridge(ctx, t, s.GetHostURL(), netCtl, locator, storeKey, func(bridge *bridge.Bridge, _ *bridge.Mocks) {
+			userLoginAndSync(ctx, t, bridge, "user", password)
+			info, err := bridge.GetUserInfo(userID)
+			require.NoError(t, err)
+			require.Equal(t, 2, len(info.Addresses))
+			require.Equal(t, info.Addresses[0], "user@proton.local")
+			require.Equal(t, info.Addresses[1], "user2@external.com")
+		})
+	})
+}
+
 // getErr returns the error that was passed to it.
 func getErr[T any](_ T, err error) error {
 	return err
--- a/internal/dialer/dialer_basic.go
+++ b/internal/dialer/dialer_basic.go
@ -22,6 +22,8 @@ import (
 	"crypto/tls"
 	"net"
 	"net/http"
+	"net/url"
+	"strings"
 	"time"
 )

@ -29,6 +31,11 @@ type TLSDialer interface {
 	DialTLSContext(ctx context.Context, network, address string) (conn net.Conn, err error)
 }

+type SecureTLSDialer interface {
+	DialTLSContext(ctx context.Context, network, address string) (conn net.Conn, err error)
+	ShouldSkipCertificateChainVerification(address string) bool
+}
+
 func SetBasicTransportTimeouts(t *http.Transport) {
 	t.MaxIdleConns = 100
 	t.MaxIdleConnsPerHost = 100
@ -71,6 +78,35 @@ func NewBasicTLSDialer(hostURL string) *BasicTLSDialer {
 	}
 }

+func extractDomain(hostname string) string {
+	parts := strings.Split(hostname, ".")
+	if len(parts) >= 2 {
+		return strings.Join(parts[len(parts)-2:], ".")
+	}
+	return hostname
+}
+
+// ShouldSkipCertificateChainVerification determines whether certificate chain validation should be skipped.
+// It compares the domain of the requested address with the configured host URL domain.
+// Returns true if the domains don't match (skip verification), false if they do (perform verification).
+//
+// NOTE: This assumes single-part TLDs (.com, .me) and won't handle multi-part TLDs correctly.
+func (d *BasicTLSDialer) ShouldSkipCertificateChainVerification(address string) bool {
+	parsedURL, err := url.Parse(d.hostURL)
+	if err != nil {
+		return true
+	}
+
+	addressHost, _, err := net.SplitHostPort(address)
+	if err != nil {
+		addressHost = address
+	}
+
+	hostDomain := extractDomain(parsedURL.Host)
+	addressDomain := extractDomain(addressHost)
+	return addressDomain != hostDomain
+}
+
 // DialTLSContext returns a connection to the given address using the given network.
 func (d *BasicTLSDialer) DialTLSContext(ctx context.Context, network, address string) (conn net.Conn, err error) {
 	return (&tls.Dialer{
@ -78,7 +114,7 @@ func (d *BasicTLSDialer) DialTLSContext(ctx context.Context, network, address st
 			Timeout: 30 * time.Second,
 		},
 		Config: &tls.Config{
-			InsecureSkipVerify: address != d.hostURL, //nolint:gosec
+			InsecureSkipVerify: d.ShouldSkipCertificateChainVerification(address), //nolint:gosec
 		},
 	}).DialContext(ctx, network, address)
 }
--- a/internal/dialer/dialer_basic_test.go
+++ b/internal/dialer/dialer_basic_test.go
@ -0,0 +1,134 @@
+// Copyright (c) 2025 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package dialer
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestBasicTLSDialer_ShouldSkipCertificateChainVerification(t *testing.T) {
+	tests := []struct {
+		hostURL  string
+		address  string
+		expected bool
+	}{
+		{
+			hostURL:  "https://mail-api.proton.me",
+			address:  "mail-api.proton.me:443",
+			expected: false,
+		},
+		{
+			hostURL:  "https://proton.me",
+			address:  "proton.me",
+			expected: false,
+		},
+		{
+			hostURL:  "https://api.proton.me",
+			address:  "mail.proton.me:443",
+			expected: false,
+		},
+		{
+			hostURL:  "https://proton.me",
+			address:  "mail-api.proton.me:443",
+			expected: false,
+		},
+		{
+			hostURL:  "https://mail-api.proton.me",
+			address:  "proton.me:443",
+			expected: false,
+		},
+		{
+			hostURL:  "https://mail.google.com",
+			address:  "mail-api.proton.me:443",
+			expected: true,
+		},
+		{
+			hostURL:  "https://mail-api.protonmail.com",
+			address:  "mail-api.proton.me:443",
+			expected: true,
+		},
+		{
+			hostURL:  "https://proton.me",
+			address:  "google.com:443",
+			expected: true,
+		},
+		{
+			hostURL:  "https://proton.me",
+			address:  "proton.com:443",
+			expected: true,
+		},
+		{
+			hostURL:  "https://proton.me",
+			address:  "example.me:443",
+			expected: true,
+		},
+		{
+			hostURL:  "https://proton.me",
+			address:  "mail.example.com:443",
+			expected: true,
+		},
+		{
+			hostURL:  "https://proton.me",
+			address:  "proton.me",
+			expected: false,
+		},
+		{
+			hostURL:  "https://proton.me:8080",
+			address:  "proton.me:443",
+			expected: true,
+		},
+		{
+			hostURL:  "https://proton.me/api/v1",
+			address:  "proton.me:443",
+			expected: false,
+		},
+		{
+			hostURL:  "https://proton.black",
+			address:  "mail-api.pascal.proton.black",
+			expected: false,
+		},
+		{
+			hostURL:  "https://mail-api.pascal.proton.black",
+			address:  "mail-api.pascal.proton.black",
+			expected: false,
+		},
+		{
+			hostURL:  "https://mail-api.pascal.proton.black",
+			address:  "proton.black:332",
+			expected: false,
+		},
+		{
+			hostURL:  "https://mail-api.pascal.proton.black",
+			address:  "proton.me",
+			expected: true,
+		},
+		{
+			hostURL:  "https://mail-api.pascal.proton.black",
+			address:  "proton.me:332",
+			expected: true,
+		},
+	}
+
+	for _, tt := range tests {
+		dialer := NewBasicTLSDialer(tt.hostURL)
+		result := dialer.ShouldSkipCertificateChainVerification(tt.address)
+		require.Equal(t, tt.expected, result)
+	}
+}
--- a/internal/dialer/dialer_pinning.go
+++ b/internal/dialer/dialer_pinning.go
@ -50,12 +50,12 @@ var TrustedAPIPins = []string{ //nolint:gochecknoglobals
 }

 // TLSReportURI is the address where TLS reports should be sent.
-const TLSReportURI = "https://reports.protonmail.ch/reports/tls"
+const TLSReportURI = "https://reports.proton.me/reports/tls"

 // PinningTLSDialer wraps a TLSDialer to check fingerprints after connecting and
 // to report errors if the fingerprint check fails.
 type PinningTLSDialer struct {
-	dialer     TLSDialer
+	dialer     SecureTLSDialer
 	pinChecker PinChecker
 	reporter   Reporter
 	tlsIssueCh chan struct{}
@ -68,13 +68,13 @@ type Reporter interface {

 // PinChecker is used to check TLS keys of connections.
 type PinChecker interface {
-	CheckCertificate(conn net.Conn) error
+	CheckCertificate(conn net.Conn, certificateChainVerificationSkipped bool) error
 }

 // NewPinningTLSDialer constructs a new dialer which only returns TCP connections to servers
 // which present known certificates.
 // It checks pins using the given pinChecker and reports issues using the given reporter.
-func NewPinningTLSDialer(dialer TLSDialer, reporter Reporter, pinChecker PinChecker) *PinningTLSDialer {
+func NewPinningTLSDialer(dialer SecureTLSDialer, reporter Reporter, pinChecker PinChecker) *PinningTLSDialer {
 	return &PinningTLSDialer{
 		dialer:     dialer,
 		pinChecker: pinChecker,
@ -85,6 +85,7 @@ func NewPinningTLSDialer(dialer TLSDialer, reporter Reporter, pinChecker PinChec

 // DialTLSContext dials the given network/address, returning an error if the certificates don't match the trusted pins.
 func (p *PinningTLSDialer) DialTLSContext(ctx context.Context, network, address string) (net.Conn, error) {
+	shouldSkipCertificateChainVerification := p.dialer.ShouldSkipCertificateChainVerification(address)
 	conn, err := p.dialer.DialTLSContext(ctx, network, address)
 	if err != nil {
 		return nil, err
@ -95,7 +96,7 @@ func (p *PinningTLSDialer) DialTLSContext(ctx context.Context, network, address
 		return nil, err
 	}

-	if err := p.pinChecker.CheckCertificate(conn); err != nil {
+	if err := p.pinChecker.CheckCertificate(conn, shouldSkipCertificateChainVerification); err != nil {
 		if tlsConn, ok := conn.(*tls.Conn); ok && p.reporter != nil {
 			p.reporter.ReportCertIssue(TLSReportURI, host, port, tlsConn.ConnectionState())
 		}
--- a/internal/dialer/dialer_pinning_checker.go
+++ b/internal/dialer/dialer_pinning_checker.go
@ -41,3 +41,15 @@ func NewTLSPinChecker(trustedPins []string) *TLSPinChecker {
 func certFingerprint(cert *x509.Certificate) string {
 	return fmt.Sprintf(`pin-sha256=%q`, algo.HashBase64SHA256(string(cert.RawSubjectPublicKeyInfo)))
 }
+
+func (p *TLSPinChecker) isCertFoundInKnownPins(cert *x509.Certificate) bool {
+	fingerprint := certFingerprint(cert)
+
+	for _, pin := range p.trustedPins {
+		if pin == fingerprint {
+			return true
+		}
+	}
+
+	return false
+}
--- a/internal/dialer/dialer_pinning_checker_default.go
+++ b/internal/dialer/dialer_pinning_checker_default.go
@ -25,8 +25,8 @@ import (
 	"net"
 )

-// CheckCertificate returns whether the connection presents a known TLS certificate.
-func (p *TLSPinChecker) CheckCertificate(conn net.Conn) error {
+// CheckCertificate verifies that the connection presents a known pinned leaf TLS certificate.
+func (p *TLSPinChecker) CheckCertificate(conn net.Conn, certificateChainVerificationSkipped bool) error {
 	tlsConn, ok := conn.(*tls.Conn)
 	if !ok {
 		return errors.New("connection is not a TLS connection")
@ -34,14 +34,31 @@ func (p *TLSPinChecker) CheckCertificate(conn net.Conn) error {

 	connState := tlsConn.ConnectionState()

-	for _, peerCert := range connState.PeerCertificates {
-		fingerprint := certFingerprint(peerCert)
+	// When certificate chain verification is enabled (e.g., for known API hosts), we expect the TLS handshake to produce verified chains.
+	// We then validate that the leaf certificate of at least one verified chain matches a known pinned public key.
+	if !certificateChainVerificationSkipped {
+		if len(connState.VerifiedChains) == 0 {
+			return errors.New("no verified certificate chains")
+		}

-		for _, pin := range p.trustedPins {
-			if pin == fingerprint {
+		for _, chain := range connState.VerifiedChains {
+			// Check if the leaf certificate is one of the trusted pins.
+			if p.isCertFoundInKnownPins(chain[0]) {
 				return nil
 			}
 		}
+
+		return ErrTLSMismatch
+	}
+
+	// When certificate chain verification is skipped (e.g., for DoH proxies using self-signed certs),
+	// we only validate the leaf certificate against known pinned public keys.
+	if len(connState.PeerCertificates) == 0 {
+		return errors.New("no peer certificates available")
+	}
+
+	if p.isCertFoundInKnownPins(connState.PeerCertificates[0]) {
+		return nil
 	}

 	return ErrTLSMismatch
--- a/internal/dialer/dialer_pinning_checker_qa.go
+++ b/internal/dialer/dialer_pinning_checker_qa.go
@ -23,6 +23,6 @@ import "net"

 // CheckCertificate returns whether the connection presents a known TLS certificate.
 // The QA implementation always returns nil.
-func (p *TLSPinChecker) CheckCertificate(conn net.Conn) error {
+func (p *TLSPinChecker) CheckCertificate(conn net.Conn, _ bool) error {
 	return nil
 }
--- a/internal/dialer/dialer_pinning_test.go
+++ b/internal/dialer/dialer_pinning_test.go
@ -64,8 +64,7 @@ func TestTLSPinInvalid(t *testing.T) {
 	checkTLSIssueHandler(t, 1, called)
 }

-// Disabled for now we'll need to patch this up.
-func _TestTLSPinNoMatch(t *testing.T) { //nolint:unused
+func TestTLSPinNoMatch(t *testing.T) {
 	skipIfProxyIsSet(t)

 	called, _, reporter, checker, cm := createClientWithPinningDialer(getRootURL())
@ -91,13 +90,12 @@ func TestTLSSignedCertWrongPublicKey(t *testing.T) {
 	r.Error(t, err, "expected dial to fail because of wrong public key")
 }

-// GODT-2293 bump badssl cert and re enable this.
-func _TestTLSSignedCertTrustedPublicKey(t *testing.T) { //nolint:unused,deadcode
+func TestTLSSignedCertTrustedPublicKey(t *testing.T) {
 	skipIfProxyIsSet(t)

 	_, dialer, _, checker, _ := createClientWithPinningDialer("")
 	copyTrustedPins(checker)
-	checker.trustedPins = append(checker.trustedPins, `pin-sha256="LwnIKjNLV3z243ap8y0yXNPghsqE76J08Eq3COvUt2E="`)
+	checker.trustedPins = append(checker.trustedPins, `pin-sha256="FlvTPG/nIMKtOj9nelnEjujwSZ5EDyfiKYxZgbXREls="`)
 	_, err := dialer.DialTLSContext(context.Background(), "tcp", "rsa4096.badssl.com:443")
 	r.NoError(t, err, "expected dial to succeed because public key is known and cert is signed by CA")
 }
--- a/internal/events/update.go
+++ b/internal/events/update.go
@ -24,14 +24,35 @@ import (
 )

 // UpdateLatest is published when the latest version of bridge is known.
+// It is only used for updating the release notes and landing page URLs.
 type UpdateLatest struct {
 	eventBase

-	Version updater.VersionInfo
+	// VersionLegacy - holds Update version information; corresponding to the old update structure and logic;
+	VersionLegacy updater.VersionInfoLegacy
+
+	// Release - holds Release version data; part of the new update logic as of BRIDGE-309.
+	Release updater.Release
+}
+
+func (event UpdateLatest) GetLatestVersion() string {
+	var latestVersion string
+	if !event.VersionLegacy.IsEmpty() {
+		latestVersion = event.VersionLegacy.Version.String()
+	} else if !event.Release.IsEmpty() {
+		latestVersion = event.Release.Version.String()
+	}
+	return latestVersion
 }

 func (event UpdateLatest) String() string {
-	return fmt.Sprintf("UpdateLatest: Version: %s", event.Version.Version)
+	if !event.VersionLegacy.IsEmpty() {
+		return fmt.Sprintf("UpdateLatest: Version: %s", event.VersionLegacy.Version)
+	}
+	if !event.Release.IsEmpty() {
+		return fmt.Sprintf("UpdateLatest: Version: %s", event.Release.Version)
+	}
+	return ""
 }

 // UpdateAvailable is published when an update is available.
@ -40,7 +61,11 @@ func (event UpdateLatest) String() string {
 type UpdateAvailable struct {
 	eventBase

-	Version updater.VersionInfo
+	// VersionLegacy - holds Update version information; corresponding to the old update structure and logic;
+	VersionLegacy updater.VersionInfoLegacy
+
+	// Release - holds Release version data; part of the new update logic as of BRIDGE-309.
+	Release updater.Release

 	// Compatible is true if the update can be installed automatically.
 	Compatible bool
@ -49,8 +74,23 @@ type UpdateAvailable struct {
 	Silent bool
 }

+func (event UpdateAvailable) GetLatestVersion() string {
+	var latestVersion string
+	if !event.VersionLegacy.IsEmpty() {
+		latestVersion = event.VersionLegacy.Version.String()
+	} else if !event.Release.IsEmpty() {
+		latestVersion = event.Release.Version.String()
+	}
+	return latestVersion
+}
+
 func (event UpdateAvailable) String() string {
-	return fmt.Sprintf("UpdateAvailable: Version %s, Compatible: %t, Silent: %t", event.Version.Version, event.Compatible, event.Silent)
+	if !event.Release.IsEmpty() {
+		return fmt.Sprintf("UpdateAvailable: Version %s, Compatible: %t, Silent: %t", event.Release.Version, event.Compatible, event.Silent)
+	} else if !event.VersionLegacy.IsEmpty() {
+		return fmt.Sprintf("UpdateAvailable: Version %s, Compatible: %t, Silent: %t", event.VersionLegacy.Version, event.Compatible, event.Silent)
+	}
+	return ""
 }

 // UpdateNotAvailable is published when no update is available.
@ -62,45 +102,70 @@ func (event UpdateNotAvailable) String() string {
 	return "UpdateNotAvailable"
 }

-// UpdateInstalling is published when bridge begins installing an update.
-type UpdateInstalling struct {
-	eventBase
-
-	Version updater.VersionInfo
-
-	Silent bool
-}
-
-func (event UpdateInstalling) String() string {
-	return fmt.Sprintf("UpdateInstalling: Version %s, Silent: %t", event.Version.Version, event.Silent)
-}
-
 // UpdateInstalled is published when an update has been installed.
 type UpdateInstalled struct {
 	eventBase

-	Version updater.VersionInfo
+	// VersionLegacy - holds Update version information; corresponding to the old update structure and logic;
+	VersionLegacy updater.VersionInfoLegacy
+
+	// Release - holds Release version data; part of the new update logic as of BRIDGE-309.
+	Release updater.Release

 	Silent bool
 }

+func (event UpdateInstalled) GetLatestVersion() string {
+	var latestVersion string
+	if !event.VersionLegacy.IsEmpty() {
+		latestVersion = event.VersionLegacy.Version.String()
+	} else if !event.Release.IsEmpty() {
+		latestVersion = event.Release.Version.String()
+	}
+	return latestVersion
+}
+
 func (event UpdateInstalled) String() string {
-	return fmt.Sprintf("UpdateInstalled: Version %s, Silent: %t", event.Version.Version, event.Silent)
+	if !event.Release.IsEmpty() {
+		return fmt.Sprintf("UpdateInstalled: Version %s, Silent: %t", event.Release.Version, event.Silent)
+	} else if !event.VersionLegacy.IsEmpty() {
+		return fmt.Sprintf("UpdateInstalled: Version %s, Silent: %t", event.VersionLegacy.Version, event.Silent)
+	}
+	return ""
 }

 // UpdateFailed is published when an update fails to be installed.
 type UpdateFailed struct {
 	eventBase

-	Version updater.VersionInfo
+	// VersionLegacy - holds Update version information; corresponding to the old update structure and logic;
+	VersionLegacy updater.VersionInfoLegacy
+
+	// Release - holds Release version data; part of the new update logic as of BRIDGE-309.
+	Release updater.Release

 	Silent bool

 	Error error
 }

+func (event UpdateFailed) GetLatestVersion() string {
+	var latestVersion string
+	if !event.VersionLegacy.IsEmpty() {
+		latestVersion = event.VersionLegacy.Version.String()
+	} else if !event.Release.IsEmpty() {
+		latestVersion = event.Release.Version.String()
+	}
+	return latestVersion
+}
+
 func (event UpdateFailed) String() string {
-	return fmt.Sprintf("UpdateFailed: Version %s, Silent: %t, Error: %s", event.Version.Version, event.Silent, event.Error)
+	if !event.Release.IsEmpty() {
+		return fmt.Sprintf("UpdateFailed: Version %s, Silent: %t, Error: %s", event.Release.Version, event.Silent, event.Error)
+	} else if !event.VersionLegacy.IsEmpty() {
+		return fmt.Sprintf("UpdateFailed: Version %s, Silent: %t, Error: %s", event.VersionLegacy.Version, event.Silent, event.Error)
+	}
+	return ""
 }

 // UpdateForced is published when the bridge version is too old and must be updated.
--- a/internal/frontend/bridge-gui/bridge-gui/BridgeApp.cpp
+++ b/internal/frontend/bridge-gui/bridge-gui/BridgeApp.cpp
@ -29,7 +29,7 @@ using namespace bridgepp;
 //****************************************************************************************************************************************************
 BridgeApp::BridgeApp(int &argc, char **argv)
    : QApplication(argc, argv) {
-
+        setAttribute(Qt::AA_DontShowIconsInMenus, false);
 }


--- a/internal/frontend/bridge-gui/bridge-gui/DeployDarwin.cmake
+++ b/internal/frontend/bridge-gui/bridge-gui/DeployDarwin.cmake
@ -24,15 +24,33 @@ cmake_minimum_required(VERSION 3.22)
 install(SCRIPT ${deploy_script})

 # QML
-install(DIRECTORY "${QT_DIR}/qml/Qt"
-        DESTINATION "${CMAKE_INSTALL_PREFIX}/bridge-gui.app/Contents/MacOS")
+install(DIRECTORY "${QT_DIR}/qml/Qt/labs/platform"
+        DESTINATION "${CMAKE_INSTALL_PREFIX}/bridge-gui.app/Contents/MacOS/Qt/labs")
 install(DIRECTORY "${QT_DIR}/qml/QtQml"
        DESTINATION "${CMAKE_INSTALL_PREFIX}/bridge-gui.app/Contents/MacOS")
 install(DIRECTORY "${QT_DIR}/qml/QtQuick"
-        DESTINATION "${CMAKE_INSTALL_PREFIX}/bridge-gui.app/Contents/MacOS")
+        DESTINATION "${CMAKE_INSTALL_PREFIX}/bridge-gui.app/Contents/MacOS"
+        PATTERN "VirtualKeyboard" EXCLUDE
+        PATTERN "Effects" EXCLUDE
+        PATTERN "LocalStorage" EXCLUDE
+        PATTERN "NativeStyle" EXCLUDE
+        PATTERN "Particles" EXCLUDE
+        PATTERN "Scene2D" EXCLUDE
+        PATTERN "Scene3D" EXCLUDE
+        PATTERN "Shapes" EXCLUDE
+        PATTERN "Timeline" EXCLUDE
+        PATTERN "VectorImage" EXCLUDE
+
+        PATTERN "Controls/FluentWinUI3" EXCLUDE
+        PATTERN "Controls/designer" EXCLUDE
+        PATTERN "Controls/Fusion" EXCLUDE
+        PATTERN "Controls/Imagine" EXCLUDE
+        PATTERN "Controls/Material" EXCLUDE
+        PATTERN "Controls/Universal" EXCLUDE
+        PATTERN "Controls/iOS" EXCLUDE
+        PATTERN "Controls/macOS" EXCLUDE)
+
 # FRAMEWORKS
-install(DIRECTORY "${QT_DIR}/lib/QtQmlWorkerScript.framework"
-        DESTINATION "${CMAKE_INSTALL_PREFIX}/bridge-gui.app/Contents/Frameworks")
 install(DIRECTORY "${QT_DIR}/lib/QtQuickControls2Impl.framework"
        DESTINATION "${CMAKE_INSTALL_PREFIX}/bridge-gui.app/Contents/Frameworks")
 install(DIRECTORY "${QT_DIR}/lib/QtQuickLayouts.framework"
@ -43,6 +61,14 @@ install(DIRECTORY "${QT_DIR}/lib/QtQuickDialogs2QuickImpl.framework"
        DESTINATION "${CMAKE_INSTALL_PREFIX}/bridge-gui.app/Contents/Frameworks")
 install(DIRECTORY "${QT_DIR}/lib/QtQuickDialogs2Utils.framework"
        DESTINATION "${CMAKE_INSTALL_PREFIX}/bridge-gui.app/Contents/Frameworks")
+# ADDITIONAL FRAMEWORKS FOR Qt 6.8
+install(DIRECTORY "${QT_DIR}/lib/QtQuickControls2Basic.framework"
+        DESTINATION "${CMAKE_INSTALL_PREFIX}/bridge-gui.app/Contents/Frameworks")
+install(DIRECTORY "${QT_DIR}/lib/QtLabsPlatform.framework"
+        DESTINATION "${CMAKE_INSTALL_PREFIX}/bridge-gui.app/Contents/Frameworks")
+install(DIRECTORY "${QT_DIR}/lib/QtQuickControls2BasicStyleImpl.framework"
+        DESTINATION "${CMAKE_INSTALL_PREFIX}/bridge-gui.app/Contents/Frameworks")
+
 # PLUGINS
 install(FILES "${QT_DIR}/plugins/imageformats/libqsvg.dylib"
        DESTINATION "${CMAKE_INSTALL_PREFIX}/bridge-gui.app/Contents/PlugIns/imageformats")
--- a/internal/frontend/bridge-gui/bridge-gui/DeployLinux.cmake
+++ b/internal/frontend/bridge-gui/bridge-gui/DeployLinux.cmake
@ -54,9 +54,9 @@ AppendQt6Lib("libQt6Gui.so.6")
 AppendQt6Lib("libQt6Core.so.6")
 AppendQt6Lib("libQt6QuickTemplates2.so.6")
 AppendQt6Lib("libQt6DBus.so.6")
-AppendQt6Lib("libicui18n.so.56")
-AppendQt6Lib("libicuuc.so.56")
-AppendQt6Lib("libicudata.so.56")
+AppendQt6Lib("libicui18n.so.73")
+AppendQt6Lib("libicuuc.so.73")
+AppendQt6Lib("libicudata.so.73")
 AppendQt6Lib("libQt6XcbQpa.so.6")
 AppendQt6Lib("libQt6WaylandClient.so.6")
 AppendQt6Lib("libQt6WlShellIntegration.so.6")
@ -68,6 +68,10 @@ AppendQt6Lib("libQt6PrintSupport.so.6")
 AppendQt6Lib("libQt6Xml.so.6")
 AppendQt6Lib("libQt6OpenGLWidgets.so.6")
 AppendQt6Lib("libQt6QuickWidgets.so.6")
+AppendQt6Lib("libQt6QmlMeta.so.6")
+AppendQt6Lib("libQt6LabsPlatform.so.6")
+AppendQt6Lib("libQt6QuickControls2Basic.so.6")
+AppendQt6Lib("libQt6QuickControls2BasicStyleImpl.so.6")

 # QML dependencies
 AppendQt6Lib("libQt6QmlWorkerScript.so.6")
--- a/internal/frontend/bridge-gui/bridge-gui/DeployWindows.cmake
+++ b/internal/frontend/bridge-gui/bridge-gui/DeployWindows.cmake
@ -57,20 +57,36 @@ AppendVCPKGLib("re2.dll")
 AppendVCPKGLib("sentry.dll")
 AppendVCPKGLib("zlib1.dll")
 # QML DLLs
-AppendQt6Lib("Qt6QmlWorkerScript.dll")
 AppendQt6Lib("Qt6Widgets.dll")
 AppendQt6Lib("Qt6QuickControls2Impl.dll")
 AppendQt6Lib("Qt6QuickLayouts.dll")
 AppendQt6Lib("Qt6QuickDialogs2.dll")
 AppendQt6Lib("Qt6QuickDialogs2QuickImpl.dll")
 AppendQt6Lib("Qt6QuickDialogs2Utils.dll")
+AppendQt6Lib("Qt6LabsPlatform.dll")
+AppendQt6Lib("Qt6QuickControls2.dll")
+AppendQt6Lib("Qt6QuickControls2Basic.dll")

 install(FILES ${DEPLOY_LIBS} DESTINATION "${CMAKE_INSTALL_PREFIX}")

 # QML PlugIns
 install(DIRECTORY ${QT_DIR}/qml/Qt/labs/platform DESTINATION "${CMAKE_INSTALL_PREFIX}/Qt/labs/")
 install(DIRECTORY ${QT_DIR}/qml/QtQml DESTINATION "${CMAKE_INSTALL_PREFIX}")
-install(DIRECTORY ${QT_DIR}/qml/QtQuick DESTINATION "${CMAKE_INSTALL_PREFIX}")
+install(DIRECTORY ${QT_DIR}/qml/QtQuick DESTINATION "${CMAKE_INSTALL_PREFIX}"
+        PATTERN "Effects" EXCLUDE
+        PATTERN "LocalStorage" EXCLUDE
+        PATTERN "NativeStyle" EXCLUDE
+        PATTERN "Particles" EXCLUDE
+        PATTERN "Shapes" EXCLUDE
+        PATTERN "VectorImage" EXCLUDE
+
+        PATTERN "Controls/designer" EXCLUDE
+        PATTERN "Controls/FluentWinUI3" EXCLUDE
+        PATTERN "Controls/Fusion" EXCLUDE
+        PATTERN "Controls/Imagine" EXCLUDE
+        PATTERN "Controls/Material" EXCLUDE
+        PATTERN "Controls/Universal" EXCLUDE
+        PATTERN "Controls/Windows" EXCLUDE)

 # crash handler utils
 install(PROGRAMS "${VCPKG_INSTALLED_DIR}/${VCPKG_TARGET_TRIPLET}/tools/sentry-native/crashpad_handler.exe" DESTINATION "${CMAKE_INSTALL_PREFIX}")
--- a/internal/frontend/bridge-gui/bridge-gui/qml/ConfigurationItem.qml
+++ b/internal/frontend/bridge-gui/bridge-gui/qml/ConfigurationItem.qml
@ -58,9 +58,9 @@ Item {
            }
            ColorImage {
                color: root.colorScheme.text_norm
-                height: root.colorScheme.body_font_size
+                height: ProtonStyle.body_font_size
                source: "/qml/icons/ic-copy.svg"
-                sourceSize.height: root.colorScheme.body_font_size
+                sourceSize.height: ProtonStyle.body_font_size

                MouseArea {
                    anchors.fill: parent
--- a/internal/frontend/bridge-gui/bridge-gui/qml/GeneralSettings.qml
+++ b/internal/frontend/bridge-gui/bridge-gui/qml/GeneralSettings.qml
@ -86,9 +86,9 @@ SettingsView {
        ColorImage {
            Layout.alignment: Qt.AlignCenter
            color: root.colorScheme.interaction_norm
-            height: root.colorScheme.body_font_size
+            height: ProtonStyle.body_font_size
            source: root._isAdvancedShown ? "/qml/icons/ic-chevron-down.svg" : "/qml/icons/ic-chevron-right.svg"
-            sourceSize.height: root.colorScheme.body_font_size
+            sourceSize.height: ProtonStyle.body_font_size

            MouseArea {
                anchors.fill: parent
--- a/internal/frontend/bridge-gui/bridge-gui/qml/Proton/Toggle.qml
+++ b/internal/frontend/bridge-gui/bridge-gui/qml/Proton/Toggle.qml
@ -72,9 +72,9 @@ Item {
            ColorImage {
                anchors.centerIn: parent
                color: root.colorScheme.background_norm
-                height: root.colorScheme.body_font_size
+                height: ProtonStyle.body_font_size
                source: "/qml/icons/ic-check.svg"
-                sourceSize.height: root.colorScheme.body_font_size
+                sourceSize.height: ProtonStyle.body_font_size
                visible: root.checked
            }
        }
@ -82,9 +82,9 @@ Item {
            id: loader
            anchors.centerIn: parent
            color: root.colorScheme.text_norm
-            height: root.colorScheme.body_font_size
+            height: ProtonStyle.body_font_size
            source: "/qml/icons/Loader_16.svg"
-            sourceSize.height: root.colorScheme.body_font_size
+            sourceSize.height: ProtonStyle.body_font_size
            visible: root.loading

            RotationAnimation {
--- a/internal/frontend/bridge-gui/bridge-gui/qml/SetupWizard/Login.qml
+++ b/internal/frontend/bridge-gui/bridge-gui/qml/SetupWizard/Login.qml
@ -271,7 +271,10 @@ FocusScope {
                        usernameTextField.enabled = false;
                        passwordTextField.enabled = false;
                        loading = true;
-                        Backend.login(usernameTextField.text, Qt.btoa(passwordTextField.text));
+
+                        let usernameTextFiltered = usernameTextField.text.replace(/[\n\r]+$/, "");
+                        let passwordTextFiltered = passwordTextField.text.replace(/[\n\r]+$/, "");
+                        Backend.login(usernameTextFiltered, Qt.btoa(passwordTextFiltered));
                    }

                    Layout.fillWidth: true
--- a/internal/frontend/cli/frontend.go
+++ b/internal/frontend/cli/frontend.go
@ -482,16 +482,16 @@ func (f *frontendCLI) watchEvents(eventCh <-chan events.Event) { // nolint:gocyc

 		case events.UpdateAvailable:
 			if !event.Compatible {
-				f.Printf("A new version (%v) is available but it cannot be installed automatically.\n", event.Version.Version)
+				f.Printf("A new version (%v) is available but it cannot be installed automatically.\n", event.GetLatestVersion())
 			} else if !event.Silent {
-				f.Printf("A new version (%v) is available.\n", event.Version.Version)
+				f.Printf("A new version (%v) is available.\n", event.GetLatestVersion())
 			}

 		case events.UpdateInstalled:
-			f.Printf("A new version (%v) was installed.\n", event.Version.Version)
+			f.Printf("A new version (%v) was installed.\n", event.GetLatestVersion())

 		case events.UpdateFailed:
-			f.Printf("A new version (%v) failed to be installed (%v).\n", event.Version.Version, event.Error)
+			f.Printf("A new version (%v) failed to be installed (%v).\n", event.GetLatestVersion(), event.Error)

 		case events.UpdateForced:
 			f.notifyNeedUpgrade()
--- a/internal/frontend/grpc/service.go
+++ b/internal/frontend/grpc/service.go
@ -78,11 +78,13 @@ type Service struct { // nolint:structcheck
 	eventCh      <-chan events.Event
 	quitCh       <-chan struct{}

-	latest     updater.VersionInfo
-	latestLock safe.RWMutex
+	latestLegacy updater.VersionInfoLegacy
+	latest       updater.Release
+	latestLock   safe.RWMutex

-	target     updater.VersionInfo
-	targetLock safe.RWMutex
+	targetLegacy updater.VersionInfoLegacy
+	target       updater.Release
+	targetLock   safe.RWMutex

 	authClient              *proton.Client
 	auth                    proton.Auth
@ -168,11 +170,13 @@ func NewService(
 		eventCh:      eventCh,
 		quitCh:       quitCh,

-		latest:     updater.VersionInfo{},
-		latestLock: safe.NewRWMutex(),
+		latestLegacy: updater.VersionInfoLegacy{},
+		latest:       updater.Release{},
+		latestLock:   safe.NewRWMutex(),

-		target:     updater.VersionInfo{},
-		targetLock: safe.NewRWMutex(),
+		targetLegacy: updater.VersionInfoLegacy{},
+		target:       updater.Release{},
+		targetLock:   safe.NewRWMutex(),

 		log:                logrus.WithField("pkg", "grpc"),
 		initializing:       sync.WaitGroup{},
@ -354,10 +358,11 @@ func (s *Service) watchEvents() {

 		case events.UpdateLatest:
 			safe.RLock(func() {
-				s.latest = event.Version
+				s.latestLegacy = event.VersionLegacy
+				s.latest = event.Release
 			}, s.latestLock)

-			_ = s.SendEvent(NewUpdateVersionChangedEvent())
+			_ = s.SendEvent(NewUpdateVersionChangedEvent()) // This updates the release notes page and landing page.

 		case events.UpdateAvailable:
 			switch {
@ -366,10 +371,11 @@ func (s *Service) watchEvents() {

 			case !event.Silent:
 				safe.RLock(func() {
-					s.target = event.Version
+					s.targetLegacy = event.VersionLegacy
+					s.target = event.Release
 				}, s.targetLock)

-				_ = s.SendEvent(NewUpdateManualReadyEvent(event.Version.Version.String()))
+				_ = s.SendEvent(NewUpdateManualReadyEvent(event.GetLatestVersion()))
 			}

 		case events.UpdateInstalled:
@ -391,8 +397,10 @@ func (s *Service) watchEvents() {

 			if s.latest.Version != nil {
 				latest = s.latest.Version.String()
-			} else if version, ok := s.checkLatestVersion(); ok {
-				latest = version.Version.String()
+			} else if s.latestLegacy.Version != nil {
+				latest = s.latestLegacy.Version.String()
+			} else if latestVersion, ok := s.checkLatestVersion(); ok {
+				latest = latestVersion
 			} else {
 				latest = "unknown"
 			}
@ -517,7 +525,7 @@ func (s *Service) triggerReset() {
 	s.bridge.FactoryReset(context.Background())
 }

-func (s *Service) checkLatestVersion() (updater.VersionInfo, bool) {
+func (s *Service) checkLatestVersion() (string, bool) {
 	updateCh, done := s.bridge.GetEvents(events.UpdateLatest{})
 	defer done()

@ -526,14 +534,13 @@ func (s *Service) checkLatestVersion() (updater.VersionInfo, bool) {
 	select {
 	case event := <-updateCh:
 		if latest, ok := event.(events.UpdateLatest); ok {
-			return latest.Version, true
+			return latest.GetLatestVersion(), true
 		}
-
 	case <-time.After(5 * time.Second):
 		// ...
 	}

-	return updater.VersionInfo{}, false
+	return "", false
 }

 func newTLSConfig() (*tls.Config, []byte, error) {
--- a/internal/frontend/grpc/service_methods.go
+++ b/internal/frontend/grpc/service_methods.go
@ -298,7 +298,14 @@ func (s *Service) ReleaseNotesPageLink(_ context.Context, _ *emptypb.Empty) (*wr
 		s.latestLock.RUnlock()
 	}()

-	return wrapperspb.String(s.latest.ReleaseNotesPage), nil
+	var releaseNotesPage string
+	if !s.latestLegacy.IsEmpty() {
+		releaseNotesPage = s.latestLegacy.ReleaseNotesPage
+	} else if !s.latest.IsEmpty() {
+		releaseNotesPage = s.latest.ReleaseNotesPage
+	}
+
+	return wrapperspb.String(releaseNotesPage), nil
 }

 func (s *Service) LandingPageLink(_ context.Context, _ *emptypb.Empty) (*wrapperspb.StringValue, error) {
@ -308,7 +315,14 @@ func (s *Service) LandingPageLink(_ context.Context, _ *emptypb.Empty) (*wrapper
 		s.latestLock.RUnlock()
 	}()

-	return wrapperspb.String(s.latest.LandingPage), nil
+	var landingPage string
+	if !s.latestLegacy.IsEmpty() {
+		landingPage = s.latestLegacy.LandingPage
+	} else if !s.latest.IsEmpty() {
+		landingPage = s.latest.LandingPage
+	}
+
+	return wrapperspb.String(landingPage), nil
 }

 func (s *Service) SetColorSchemeName(_ context.Context, name *wrapperspb.StringValue) (*emptypb.Empty, error) {
@ -617,7 +631,11 @@ func (s *Service) InstallUpdate(_ context.Context, _ *emptypb.Empty) (*emptypb.E
 		defer async.HandlePanic(s.panicHandler)

 		safe.RLock(func() {
-			s.bridge.InstallUpdate(s.target)
+			if !s.targetLegacy.IsEmpty() {
+				s.bridge.InstallUpdateLegacy(s.targetLegacy)
+			} else if !s.target.IsEmpty() {
+				s.bridge.InstallUpdate(s.target)
+			}
 		}, s.targetLock)
 	}()

--- a/internal/logging/pruning.go
+++ b/internal/logging/pruning.go
@ -212,7 +212,7 @@ func buildSessionInfoList(dir string) (map[SessionID]*sessionInfo, error) {
 		}
 		rx := regexp.MustCompile(`^(\d{8}_\d{9})_.*\.log$`)
 		match := rx.FindStringSubmatch(entry.Name())
-		if match == nil || len(match) < 2 {
+		if len(match) < 2 {
 			continue
 		}

--- a/internal/sentry/reporter.go
+++ b/internal/sentry/reporter.go
@ -157,7 +157,7 @@ func (r *Reporter) ReportExceptionWithContext(i interface{}, context map[string]
 	SkipDuringUnwind()

 	err := fmt.Errorf("recover: %v", i)
-	return r.scopedReport(context, func() {
+	return r.scopedReport(context, func(_ *sentry.Scope) {
 		SkipDuringUnwind()
 		if eventID := sentry.CaptureException(err); eventID != nil {
 			logrus.WithError(err).
@ -169,7 +169,20 @@ func (r *Reporter) ReportExceptionWithContext(i interface{}, context map[string]

 func (r *Reporter) ReportMessageWithContext(msg string, context map[string]interface{}) error {
 	SkipDuringUnwind()
-	return r.scopedReport(context, func() {
+	return r.scopedReport(context, func(_ *sentry.Scope) {
+		SkipDuringUnwind()
+		if eventID := sentry.CaptureMessage(msg); eventID != nil {
+			logrus.WithField("message", msg).
+				WithField("reportID", *eventID).
+				Warn("Captured message")
+		}
+	})
+}
+
+func (r *Reporter) ReportWarningWithContext(msg string, context map[string]interface{}) error {
+	SkipDuringUnwind()
+	return r.scopedReport(context, func(scope *sentry.Scope) {
+		scope.SetLevel(sentry.LevelWarning)
 		SkipDuringUnwind()
 		if eventID := sentry.CaptureMessage(msg); eventID != nil {
 			logrus.WithField("message", msg).
@ -180,7 +193,7 @@ func (r *Reporter) ReportMessageWithContext(msg string, context map[string]inter
 }

 // Report reports a sentry crash with stacktrace from all goroutines.
-func (r *Reporter) scopedReport(context map[string]interface{}, doReport func()) error {
+func (r *Reporter) scopedReport(context map[string]interface{}, doReport func(scope *sentry.Scope)) error {
 	SkipDuringUnwind()

 	if os.Getenv("PROTONMAIL_ENV") == "dev" {
@ -206,7 +219,7 @@ func (r *Reporter) scopedReport(context map[string]interface{}, doReport func())
 				map[string]sentry.Context{"bridge": contextToString(context)},
 			)
 		}
-		doReport()
+		doReport(scope)
 	})

 	if !sentry.Flush(time.Second * 10) {
@ -287,3 +300,25 @@ func contextToString(context sentry.Context) sentry.Context {

 	return res
 }
+
+type NullSentryReporter struct{}
+
+func (n NullSentryReporter) ReportException(any) error {
+	return nil
+}
+
+func (n NullSentryReporter) ReportMessage(string) error {
+	return nil
+}
+
+func (n NullSentryReporter) ReportMessageWithContext(string, reporter.Context) error {
+	return nil
+}
+
+func (n NullSentryReporter) ReportWarningWithContext(string, reporter.Context) error {
+	return nil
+}
+
+func (n NullSentryReporter) ReportExceptionWithContext(any, reporter.Context) error {
+	return nil
+}
--- a/internal/services/imapservice/conflicts.go
+++ b/internal/services/imapservice/conflicts.go
@ -0,0 +1,388 @@
+// Copyright (c) 2025 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package imapservice
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/ProtonMail/gluon/db"
+	"github.com/ProtonMail/gluon/imap"
+	"github.com/ProtonMail/gluon/reporter"
+	"github.com/ProtonMail/go-proton-api"
+	"github.com/ProtonMail/proton-bridge/v3/internal/unleash"
+	"github.com/ProtonMail/proton-bridge/v3/pkg/algo"
+	"github.com/sirupsen/logrus"
+)
+
+type GluonLabelNameProvider interface {
+	GetUserMailboxByName(ctx context.Context, addrID string, labelName []string) (imap.MailboxData, error)
+}
+
+type gluonIDProvider interface {
+	GetGluonID(addrID string) (string, bool)
+}
+
+type sentryReporter interface {
+	ReportMessageWithContext(string, reporter.Context) error
+	ReportWarningWithContext(string, reporter.Context) error
+}
+
+type apiClient interface {
+	GetLabel(ctx context.Context, labelID string, labelTypes ...proton.LabelType) (proton.Label, error)
+}
+
+type mailboxFetcherFn func(ctx context.Context, label proton.Label) (imap.MailboxData, error)
+
+type mailboxMessageCountFetcherFn func(ctx context.Context, internalMailboxID imap.InternalMailboxID) (int, error)
+
+type LabelConflictManager struct {
+	gluonLabelNameProvider GluonLabelNameProvider
+	gluonIDProvider        gluonIDProvider
+	client                 apiClient
+	reporter               sentryReporter
+	featureFlagProvider    unleash.FeatureFlagValueProvider
+}
+
+func NewLabelConflictManager(
+	gluonLabelNameProvider GluonLabelNameProvider,
+	gluonIDProvider gluonIDProvider,
+	client apiClient,
+	reporter sentryReporter,
+	featureFlagProvider unleash.FeatureFlagValueProvider) *LabelConflictManager {
+	return &LabelConflictManager{
+		gluonLabelNameProvider: gluonLabelNameProvider,
+		gluonIDProvider:        gluonIDProvider,
+		client:                 client,
+		reporter:               reporter,
+		featureFlagProvider:    featureFlagProvider,
+	}
+}
+
+func (m *LabelConflictManager) generateMailboxFetcher(connectors []*Connector) mailboxFetcherFn {
+	return func(ctx context.Context, label proton.Label) (imap.MailboxData, error) {
+		for _, updateCh := range connectors {
+			addrID, ok := m.gluonIDProvider.GetGluonID(updateCh.addrID)
+			if !ok {
+				continue
+			}
+			return m.gluonLabelNameProvider.GetUserMailboxByName(ctx, addrID, GetMailboxName(label))
+		}
+		return imap.MailboxData{}, errors.New("no gluon connectors found")
+	}
+}
+
+func (m *LabelConflictManager) generateMailboxMessageCountFetcher(connectors []*Connector) mailboxMessageCountFetcherFn {
+	return func(ctx context.Context, id imap.InternalMailboxID) (int, error) {
+		var countSum int
+		var errs []error
+		for _, conn := range connectors {
+			count, err := conn.GetMailboxMessageCount(ctx, id)
+			countSum += count
+			errs = append(errs, err)
+		}
+
+		return countSum, errors.Join(errs...)
+	}
+}
+
+type LabelConflictResolver interface {
+	ResolveConflict(ctx context.Context, label proton.Label, visited map[string]bool) (func() []imap.Update, error)
+}
+type labelConflictResolverImpl struct {
+	mailboxFetch mailboxFetcherFn
+	client       apiClient
+	reporter     sentryReporter
+	log          *logrus.Entry
+}
+
+type nullLabelConflictResolverImpl struct {
+}
+
+func (r *nullLabelConflictResolverImpl) ResolveConflict(_ context.Context, _ proton.Label, _ map[string]bool) (func() []imap.Update, error) {
+	return func() []imap.Update {
+		return []imap.Update{}
+	}, nil
+}
+
+func (m *LabelConflictManager) NewConflictResolver(connectors []*Connector) LabelConflictResolver {
+	if m.featureFlagProvider.GetFlagValue(unleash.LabelConflictResolverDisabled) {
+		return &nullLabelConflictResolverImpl{}
+	}
+
+	return &labelConflictResolverImpl{
+		mailboxFetch: m.generateMailboxFetcher(connectors),
+		client:       m.client,
+		reporter:     m.reporter,
+		log: logrus.WithFields(logrus.Fields{
+			"pkg":                "imapservice/labelConflictResolver",
+			"numberOfConnectors": len(connectors),
+		}),
+	}
+}
+
+func (r *labelConflictResolverImpl) ResolveConflict(ctx context.Context, label proton.Label, visited map[string]bool) (func() []imap.Update, error) {
+	logger := r.log.WithFields(logrus.Fields{
+		"labelID":   label.ID,
+		"labelPath": hashLabelPaths(GetMailboxName(label)),
+	})
+
+	// For system type labels we shouldn't care.
+	var updateFns []func() []imap.Update
+
+	// There's a cycle, such as in a label swap operation, we'll need to temporarily rename the label.
+	// The change will be overwritten by one of the previous recursive calls.
+	if visited[label.ID] {
+		logrus.Info("Cycle detected, applying temporary rename")
+		fn := func() []imap.Update {
+			return []imap.Update{newMailboxUpdatedOrCreated(imap.MailboxID(label.ID), getMailboxNameWithTempPrefix(label))}
+		}
+		updateFns = append(updateFns, fn)
+		return combineIMAPUpdateFns(updateFns), nil
+	}
+	visited[label.ID] = true
+
+	// Fetch the gluon mailbox data and verify whether there are conflicts with the name.
+	mailboxData, err := r.mailboxFetch(ctx, label)
+	if err != nil {
+		// Name is free, create the mailbox.
+		if db.IsErrNotFound(err) {
+			logger.Info("Label not found in DB, creating mailbox.")
+			fn := func() []imap.Update {
+				return []imap.Update{newMailboxUpdatedOrCreated(imap.MailboxID(label.ID), GetMailboxName(label))}
+			}
+			updateFns = append(updateFns, fn)
+			return combineIMAPUpdateFns(updateFns), nil
+		}
+		return combineIMAPUpdateFns(updateFns), err
+	}
+
+	// Verify whether the label name corresponds to the same label ID. If true terminate, we don't need to update.
+	if mailboxData.RemoteID == label.ID {
+		logger.Info("Mailbox name matches label ID, no conflict.")
+		return combineIMAPUpdateFns(updateFns), nil
+	}
+
+	// This means we've found a conflict. So let's log it.
+	logger = logger.WithFields(logrus.Fields{
+		"conflictingLabelID":   mailboxData.RemoteID,
+		"conflictingLabelPath": hashLabelPaths(mailboxData.BridgeName),
+	})
+	logger.Info("Label conflict found")
+
+	// If the label name belongs to some other label ID. Fetch it's state from the remote.
+	conflictingLabel, err := r.client.GetLabel(ctx, mailboxData.RemoteID, proton.LabelTypeFolder, proton.LabelTypeLabel, proton.LabelTypeSystem)
+	if err != nil {
+		// If it's not present on the remote we should delete it. And create the new label.
+		if errors.Is(err, proton.ErrNoSuchLabel) {
+			logger.Info("Conflicting label does not exist on remote. Deleting.")
+			fn := func() []imap.Update {
+				return []imap.Update{
+					imap.NewMailboxDeleted(imap.MailboxID(mailboxData.RemoteID)), // Should this be with remote ID
+					newMailboxUpdatedOrCreated(imap.MailboxID(label.ID), GetMailboxName(label)),
+				}
+			}
+			updateFns = append(updateFns, fn)
+			return combineIMAPUpdateFns(updateFns), nil
+		}
+		logger.WithError(err).Error("Failed to fetch conflicting label from remote.")
+		return combineIMAPUpdateFns(updateFns), err
+	}
+
+	// Check if the conflicting label name has changed. If not, then this is a BE inconsistency.
+	if compareLabelNames(GetMailboxName(conflictingLabel), mailboxData.BridgeName) {
+		if err := r.reporter.ReportMessageWithContext("Unexpected label conflict", reporter.Context{
+			"labelID":            label.ID,
+			"conflictingLabelID": conflictingLabel.ID,
+		}); err != nil {
+			logger.WithError(err).Error("Failed to report update error")
+		}
+
+		err := fmt.Errorf("unexpected label conflict: the name of label ID %s is already used by label ID %s", label.ID, conflictingLabel.ID)
+		return combineIMAPUpdateFns(updateFns), err
+	}
+
+	// The name of the conflicting label has changed on the remote. We need to verify that the new name does not conflict with anything else.
+	// Thus, a recursive check can be performed.
+	logger.WithField("conflictingLabelNewPath", hashLabelPaths(conflictingLabel.Path)).
+		Info("Conflicting label name has changed. Recursively resolving conflict.")
+	childUpdateFns, err := r.ResolveConflict(ctx, conflictingLabel, visited)
+	if err != nil {
+		return combineIMAPUpdateFns(updateFns), err
+	}
+	updateFns = append(updateFns, childUpdateFns)
+
+	fn := func() []imap.Update {
+		return []imap.Update{newMailboxUpdatedOrCreated(imap.MailboxID(label.ID), GetMailboxName(label))}
+	}
+	updateFns = append(updateFns, fn)
+
+	return combineIMAPUpdateFns(updateFns), nil
+}
+
+func combineIMAPUpdateFns(updateFunctions []func() []imap.Update) func() []imap.Update {
+	return func() []imap.Update {
+		var updates []imap.Update
+		for _, fn := range updateFunctions {
+			updates = append(updates, fn()...)
+		}
+		return updates
+	}
+}
+
+func compareLabelNames(labelName1, labelName2 []string) bool {
+	name1 := strings.Join(labelName1, "")
+	name2 := strings.Join(labelName2, "")
+	return name1 == name2
+}
+
+func hashLabelPaths(path []string) string {
+	return algo.HashBase64SHA256(strings.Join(path, ""))
+}
+
+type InternalLabelConflictResolver interface {
+	ResolveConflict(ctx context.Context, apiLabels map[string]proton.Label) (func() []imap.Update, error)
+}
+
+type internalLabelConflictResolverImpl struct {
+	mailboxFetch                 mailboxFetcherFn
+	mailboxMessageCountFetch     mailboxMessageCountFetcherFn
+	userLabelConflictResolver    LabelConflictResolver
+	allowNonEmptyMailboxDeletion bool
+	client                       apiClient
+	reporter                     sentryReporter
+	log                          *logrus.Entry
+}
+
+type nullInternalLabelConflictResolver struct{}
+
+func (r *nullInternalLabelConflictResolver) ResolveConflict(_ context.Context, _ map[string]proton.Label) (func() []imap.Update, error) {
+	return func() []imap.Update { return []imap.Update{} }, nil
+}
+
+func (m *LabelConflictManager) NewInternalLabelConflictResolver(connectors []*Connector) InternalLabelConflictResolver {
+	if m.featureFlagProvider.GetFlagValue(unleash.InternalLabelConflictResolverDisabled) {
+		return &nullInternalLabelConflictResolver{}
+	}
+
+	return &internalLabelConflictResolverImpl{
+		mailboxFetch:                 m.generateMailboxFetcher(connectors),
+		mailboxMessageCountFetch:     m.generateMailboxMessageCountFetcher(connectors),
+		userLabelConflictResolver:    m.NewConflictResolver(connectors),
+		allowNonEmptyMailboxDeletion: m.featureFlagProvider.GetFlagValue(unleash.ItnternalLabelConflictNonEmptyMailboxDeletion),
+		client:                       m.client,
+		reporter:                     m.reporter,
+		log: logrus.WithFields(logrus.Fields{
+			"pkg":                "imapservice/internalLabelConflictResolver",
+			"numberOfConnectors": len(connectors),
+		}),
+	}
+}
+
+func (r *internalLabelConflictResolverImpl) ResolveConflict(ctx context.Context, apiLabels map[string]proton.Label) (func() []imap.Update, error) {
+	updateFns := []func() []imap.Update{}
+
+	for _, prefix := range []string{folderPrefix, labelPrefix} {
+		internalLabel := proton.Label{
+			Path: []string{prefix},
+			ID:   prefix,
+			Name: prefix,
+		}
+
+		mbox, err := r.mailboxFetch(ctx, internalLabel)
+		if err != nil {
+			if db.IsErrNotFound(err) {
+				continue
+			}
+			return nil, err
+		}
+
+		// If the ID's match then we don't have a discrepancy.
+		if mbox.RemoteID == internalLabel.ID {
+			continue
+		}
+
+		logFields := logrus.Fields{
+			"internalLabelID":      internalLabel.ID,
+			"internalLabelName":    internalLabel.Name,
+			"conflictingLabelID":   mbox.RemoteID,
+			"conflictingLabelName": strings.Join(mbox.BridgeName, "/"),
+		}
+		reporterContext := reporter.Context(logFields)
+		logger := r.log.WithFields(logFields)
+		logger.Info("Encountered conflict, resolving.")
+
+		// There is a discrepancy, let's see if it comes from API.
+		apiLabel, ok := apiLabels[mbox.RemoteID]
+		if !ok {
+			// Label does not come from API, we should delete it.
+			// Due diligence, check if there are any messages associated with the mailbox.
+			msgCount, _ := r.mailboxMessageCountFetch(ctx, mbox.InternalID)
+			if msgCount != 0 {
+				logger.WithField("conflictingLabelMessageCount", msgCount).Info("Non-API conflicting label has associated messages")
+
+				reporterContext["conflictingLabelMessageCount"] = msgCount
+				if rerr := r.reporter.ReportWarningWithContext("Internal mailbox name conflict. Conflicting non-API label has messages.",
+					reporterContext); rerr != nil {
+					logger.WithError(rerr).Error("Failed to send report to sentry")
+				}
+
+				if !r.allowNonEmptyMailboxDeletion {
+					return combineIMAPUpdateFns(updateFns), fmt.Errorf("internal mailbox conflicting non-api label has associated messages")
+				}
+			}
+
+			fn := func() []imap.Update {
+				return []imap.Update{imap.NewMailboxDeletedSilent(imap.MailboxID(mbox.RemoteID))}
+			}
+			updateFns = append(updateFns, fn)
+			continue
+		}
+
+		reporterContext["conflictingLabelType"] = apiLabel.Type
+
+		// Label is indeed from API let's see if it's name has changed.
+		if compareLabelNames(GetMailboxName(apiLabel), internalLabel.Path) {
+			logger.Error("Conflict, same-name mailbox is returned by API")
+
+			if err := r.reporter.ReportMessageWithContext("Internal mailbox name conflict. Same-name mailbox is returned by API", reporterContext); err != nil {
+				logger.WithError(err).Error("Could not send report to sentry")
+			}
+
+			return combineIMAPUpdateFns(updateFns), fmt.Errorf("API label %s conflicts with internal label %s",
+				GetMailboxName(apiLabel),
+				strings.Join(mbox.BridgeName, "/"),
+			)
+		}
+
+		// If it's name has changed then we ought to rename it while still taking care of potential conflicts.
+		labelRenameUpdates, err := r.userLabelConflictResolver.ResolveConflict(ctx, apiLabel, make(map[string]bool))
+		if err != nil {
+			reporterContext["err"] = err.Error()
+			if rerr := r.reporter.ReportMessageWithContext("Failed to resolve internal mailbox conflict", reporterContext); rerr != nil {
+				logger.WithError(rerr).Error("Could not send report to sentry")
+			}
+			return combineIMAPUpdateFns(updateFns),
+				fmt.Errorf("failed to resolve user label conflict for '%s': %w", apiLabel.Name, err)
+		}
+		updateFns = append(updateFns, labelRenameUpdates)
+	}
+	return combineIMAPUpdateFns(updateFns), nil
+}
--- a/internal/services/imapservice/conflicts_test.go
+++ b/internal/services/imapservice/conflicts_test.go
@ -0,0 +1,961 @@
+// Copyright (c) 2025 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package imapservice_test
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"testing"
+
+	"github.com/ProtonMail/gluon/db"
+	"github.com/ProtonMail/gluon/imap"
+	"github.com/ProtonMail/gluon/reporter"
+	"github.com/ProtonMail/go-proton-api"
+	"github.com/ProtonMail/proton-bridge/v3/internal/services/imapservice"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+)
+
+type ffProviderFalse struct{}
+type ffProviderTrue struct{}
+
+func (f ffProviderFalse) GetFlagValue(_ string) bool {
+	return false
+}
+
+func (f ffProviderTrue) GetFlagValue(_ string) bool {
+	return true
+}
+
+type mockLabelNameProvider struct {
+	mock.Mock
+}
+
+func (m *mockLabelNameProvider) GetUserMailboxByName(ctx context.Context, addrID string, labelName []string) (imap.MailboxData, error) {
+	args := m.Called(ctx, addrID, labelName)
+	v, ok := args.Get(0).(imap.MailboxData)
+	if !ok {
+		return imap.MailboxData{}, fmt.Errorf("failed to assert type")
+	}
+	return v, args.Error(1)
+}
+
+type mockIDProvider struct {
+	mock.Mock
+}
+
+func (m *mockIDProvider) GetGluonID(addrID string) (string, bool) {
+	args := m.Called(addrID)
+	return args.String(0), args.Bool(1)
+}
+
+type mockAPIClient struct {
+	mock.Mock
+}
+
+func (m *mockAPIClient) GetLabel(ctx context.Context, id string, types ...proton.LabelType) (proton.Label, error) {
+	args := m.Called(ctx, id, types)
+	v, ok := args.Get(0).(proton.Label)
+	if !ok {
+		return proton.Label{}, fmt.Errorf("failed to assert type")
+	}
+	return v, args.Error(1)
+}
+
+type mockReporter struct {
+	mock.Mock
+}
+
+func (m *mockReporter) ReportMessageWithContext(msg string, ctx reporter.Context) error {
+	args := m.Called(msg, ctx)
+	return args.Error(0)
+}
+
+func (m *mockReporter) ReportWarningWithContext(msg string, ctx reporter.Context) error {
+	args := m.Called(msg, ctx)
+	return args.Error(0)
+}
+
+func TestResolveConflict_UnexpectedLabelConflict(t *testing.T) {
+	ctx := context.Background()
+	label := proton.Label{
+		ID:   "label-1",
+		Path: []string{"Work"},
+		Type: proton.LabelTypeLabel,
+	}
+	conflictingLabel := proton.Label{
+		ID:   "label-2",
+		Path: []string{"Work"},
+		Type: proton.LabelTypeLabel,
+	}
+	conflictMbox := imap.MailboxData{
+		RemoteID:   "label-2",
+		BridgeName: []string{"Labels", "Work"},
+	}
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockIDProvider := new(mockIDProvider)
+	mockClient := new(mockAPIClient)
+	mockReporter := new(mockReporter)
+
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id", imapservice.GetMailboxName(label)).
+		Return(conflictMbox, nil)
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id", true)
+	mockClient.On("GetLabel", mock.Anything, "label-2", mock.Anything).
+		Return(conflictingLabel, nil)
+	mockReporter.On("ReportMessageWithContext", "Unexpected label conflict", mock.Anything).
+		Return(nil)
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	resolver := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderFalse{}).
+		NewConflictResolver([]*imapservice.Connector{connector})
+
+	visited := make(map[string]bool)
+	_, err := resolver.ResolveConflict(ctx, label, visited)
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "unexpected label conflict")
+}
+
+func TestResolveDiscrepancy_LabelDoesNotExist(t *testing.T) {
+	ctx := context.Background()
+	label := proton.Label{
+		ID:   "label-id-1",
+		Name: "Inbox",
+		Type: proton.LabelTypeLabel,
+	}
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockIDProvider := new(mockIDProvider)
+	mockClient := new(mockAPIClient)
+	mockReporter := new(mockReporter)
+
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id-1", imapservice.GetMailboxName(label)).
+		Return(imap.MailboxData{}, db.ErrNotFound)
+
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id-1", true)
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	connectors := []*imapservice.Connector{connector}
+
+	manager := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderFalse{})
+	resolver := manager.NewConflictResolver(connectors)
+
+	visited := make(map[string]bool)
+	fn, err := resolver.ResolveConflict(ctx, label, visited)
+
+	assert.NoError(t, err)
+	updates := fn()
+	assert.Len(t, updates, 1)
+	muc, ok := updates[0].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(label.ID), muc.Mailbox.ID)
+}
+
+func TestResolveConflict_MailboxFetchError(t *testing.T) {
+	ctx := context.Background()
+	label := proton.Label{
+		ID:   "111",
+		Path: []string{"Work"},
+		Type: proton.LabelTypeLabel,
+	}
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockIDProvider := new(mockIDProvider)
+	mockClient := new(mockAPIClient)
+	mockReporter := new(mockReporter)
+
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id", imapservice.GetMailboxName(label)).
+		Return(imap.MailboxData{}, errors.New("database connection error"))
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id", true)
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	resolver := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderFalse{}).
+		NewConflictResolver([]*imapservice.Connector{connector})
+
+	visited := make(map[string]bool)
+	_, err := resolver.ResolveConflict(ctx, label, visited)
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "database connection error")
+}
+
+func TestResolveDiscrepancy_ConflictingLabelDeletedRemotely(t *testing.T) {
+	ctx := context.Background()
+	label := proton.Label{
+		ID:   "label-new",
+		Path: []string{"Work"},
+		Type: proton.LabelTypeLabel,
+	}
+	conflictMbox := imap.MailboxData{
+		RemoteID:   "label-old",
+		BridgeName: []string{"Labels", "Work"},
+	}
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockIDProvider := new(mockIDProvider)
+	mockClient := new(mockAPIClient)
+	mockReporter := new(mockReporter)
+
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id-1", imapservice.GetMailboxName(label)).
+		Return(conflictMbox, nil)
+
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id-1", true)
+
+	mockClient.On("GetLabel", mock.Anything, "label-old", mock.Anything).
+		Return(proton.Label{}, proton.ErrNoSuchLabel)
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	connectors := []*imapservice.Connector{connector}
+
+	manager := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderFalse{})
+	resolver := manager.NewConflictResolver(connectors)
+
+	visited := make(map[string]bool)
+	fn, err := resolver.ResolveConflict(ctx, label, visited)
+
+	assert.NoError(t, err)
+	updates := fn()
+	assert.Len(t, updates, 2)
+	deleted, ok := updates[0].(*imap.MailboxDeleted)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID("label-old"), deleted.MailboxID)
+
+	updated, ok := updates[1].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, "Work", updated.Mailbox.Name[len(updated.Mailbox.Name)-1])
+}
+
+func TestResolveDiscrepancy_LabelAlreadyCorrect(t *testing.T) {
+	ctx := context.Background()
+	label := proton.Label{
+		ID:   "label-id-1",
+		Name: "Personal",
+		Type: proton.LabelTypeLabel,
+	}
+	mbox := imap.MailboxData{
+		RemoteID:   "label-id-1",
+		BridgeName: []string{"Labels", "Personal"},
+	}
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockIDProvider := new(mockIDProvider)
+	mockClient := new(mockAPIClient)
+	mockReporter := new(mockReporter)
+
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id-1", imapservice.GetMailboxName(label)).
+		Return(mbox, nil)
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id-1", true)
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	connectors := []*imapservice.Connector{connector}
+
+	manager := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderFalse{})
+	resolver := manager.NewConflictResolver(connectors)
+
+	visited := make(map[string]bool)
+	fn, err := resolver.ResolveConflict(ctx, label, visited)
+
+	assert.NoError(t, err)
+	assert.Len(t, fn(), 0)
+}
+
+func TestResolveConflict_DeepNestedPath(t *testing.T) {
+	ctx := context.Background()
+	label := proton.Label{
+		ID:   "111",
+		Path: []string{"Level1", "Level2", "Level3", "DeepFolder"},
+		Type: proton.LabelTypeFolder,
+	}
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockIDProvider := new(mockIDProvider)
+	mockClient := new(mockAPIClient)
+	mockReporter := new(mockReporter)
+
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id", imapservice.GetMailboxName(label)).
+		Return(imap.MailboxData{}, db.ErrNotFound)
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id", true)
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	resolver := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderFalse{}).
+		NewConflictResolver([]*imapservice.Connector{connector})
+
+	visited := make(map[string]bool)
+	fn, err := resolver.ResolveConflict(ctx, label, visited)
+
+	assert.NoError(t, err)
+	updates := fn()
+	assert.Len(t, updates, 1)
+
+	updated, ok := updates[0].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID("111"), updated.Mailbox.ID)
+	expectedName := imapservice.GetMailboxName(label)
+	assert.Equal(t, expectedName, updated.Mailbox.Name)
+}
+
+func TestResolveLabelDiscrepancy_LabelSwap(t *testing.T) {
+	apiLabels := []proton.Label{
+		{
+			ID:   "111",
+			Path: []string{"X"},
+			Type: proton.LabelTypeLabel,
+		},
+		{
+			ID:   "222",
+			Path: []string{"Y"},
+			Type: proton.LabelTypeLabel,
+		},
+	}
+
+	gluonLabels := []imap.MailboxData{
+		{
+			RemoteID:   "111",
+			BridgeName: []string{"Labels", "Y"},
+		},
+		{
+			RemoteID:   "222",
+			BridgeName: []string{"Labels", "X"},
+		},
+	}
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockClient := new(mockAPIClient)
+	mockIDProvider := new(mockIDProvider)
+	mockReporter := new(mockReporter)
+
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id-1", true)
+
+	for _, mbox := range gluonLabels {
+		mockLabelProvider.
+			On("GetUserMailboxByName", mock.Anything, "gluon-id-1", mbox.BridgeName).
+			Return(mbox, nil)
+	}
+
+	for _, label := range apiLabels {
+		mockClient.
+			On("GetLabel", mock.Anything, label.ID, []proton.LabelType{proton.LabelTypeFolder, proton.LabelTypeLabel, proton.LabelTypeSystem}).
+			Return(label, nil)
+	}
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	connectors := []*imapservice.Connector{connector}
+
+	manager := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderFalse{})
+	resolver := manager.NewConflictResolver(connectors)
+
+	visited := make(map[string]bool)
+	fn, err := resolver.ResolveConflict(context.Background(), apiLabels[0], visited)
+	require.NoError(t, err)
+
+	updates := fn()
+	assert.NotEmpty(t, updates)
+	assert.Equal(t, 3, len(updates)) // We expect three calls to be made for a swap operation.
+
+	updateOne, ok := updates[0].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(apiLabels[0].ID), updateOne.Mailbox.ID)
+	assert.Equal(t, "tmp_X", updateOne.Mailbox.Name[len(updateOne.Mailbox.Name)-1])
+
+	updateTwo, ok := updates[1].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(apiLabels[1].ID), updateTwo.Mailbox.ID)
+	assert.Equal(t, "Y", updateTwo.Mailbox.Name[len(updateTwo.Mailbox.Name)-1])
+
+	updateThree, ok := updates[2].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(apiLabels[0].ID), updateThree.Mailbox.ID)
+	assert.Equal(t, "X", updateThree.Mailbox.Name[len(updateThree.Mailbox.Name)-1])
+}
+
+func TestResolveLabelDiscrepancy_LabelSwapExtended(t *testing.T) {
+	apiLabels := []proton.Label{
+		{
+			ID:   "111",
+			Path: []string{"X"},
+			Type: proton.LabelTypeLabel,
+		},
+		{
+			ID:   "222",
+			Path: []string{"Y"},
+			Type: proton.LabelTypeLabel,
+		},
+		{
+			ID:   "333",
+			Path: []string{"Z"},
+			Type: proton.LabelTypeLabel,
+		},
+		{
+			ID:   "444",
+			Path: []string{"D"},
+			Type: proton.LabelTypeLabel,
+		},
+	}
+
+	gluonLabels := []imap.MailboxData{
+		{
+			RemoteID:   "111",
+			BridgeName: []string{"Labels", "D"},
+		},
+		{
+			RemoteID:   "222",
+			BridgeName: []string{"Labels", "Z"},
+		},
+		{
+			RemoteID:   "333",
+			BridgeName: []string{"Labels", "Y"},
+		},
+		{
+			RemoteID:   "444",
+			BridgeName: []string{"Labels", "X"},
+		},
+	}
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockClient := new(mockAPIClient)
+	mockIDProvider := new(mockIDProvider)
+	mockReporter := new(mockReporter)
+
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id-1", true)
+
+	for _, mbox := range gluonLabels {
+		mockLabelProvider.
+			On("GetUserMailboxByName", mock.Anything, "gluon-id-1", mbox.BridgeName).
+			Return(mbox, nil)
+	}
+
+	for _, label := range apiLabels {
+		mockClient.
+			On("GetLabel", mock.Anything, label.ID, []proton.LabelType{proton.LabelTypeFolder, proton.LabelTypeLabel, proton.LabelTypeSystem}).
+			Return(label, nil)
+	}
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	connectors := []*imapservice.Connector{connector}
+
+	manager := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderFalse{})
+	resolver := manager.NewConflictResolver(connectors)
+
+	fn, err := resolver.ResolveConflict(context.Background(), apiLabels[0], make(map[string]bool))
+	require.NoError(t, err)
+
+	updates := fn()
+	assert.NotEmpty(t, updates)
+	// Three calls yet again for a swap operation.
+	assert.Equal(t, 3, len(updates))
+	updateOne, ok := updates[0].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(apiLabels[0].ID), updateOne.Mailbox.ID)
+	assert.Equal(t, "tmp_X", updateOne.Mailbox.Name[len(updateOne.Mailbox.Name)-1])
+
+	updateTwo, ok := updates[1].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(apiLabels[3].ID), updateTwo.Mailbox.ID)
+	assert.Equal(t, "D", updateTwo.Mailbox.Name[len(updateTwo.Mailbox.Name)-1])
+
+	updateThree, ok := updates[2].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(apiLabels[0].ID), updateThree.Mailbox.ID)
+	assert.Equal(t, "X", updateThree.Mailbox.Name[len(updateThree.Mailbox.Name)-1])
+
+	// Fix the secondary swap.
+	fn, err = resolver.ResolveConflict(context.Background(), apiLabels[1], make(map[string]bool))
+	require.NoError(t, err)
+
+	updates = fn()
+	assert.Equal(t, 3, len(updates))
+	updateOne, ok = updates[0].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(apiLabels[1].ID), updateOne.Mailbox.ID)
+	assert.Equal(t, "tmp_Y", updateOne.Mailbox.Name[len(updateOne.Mailbox.Name)-1])
+
+	updateTwo, ok = updates[1].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(apiLabels[2].ID), updateTwo.Mailbox.ID)
+	assert.Equal(t, "Z", updateTwo.Mailbox.Name[len(updateTwo.Mailbox.Name)-1])
+
+	updateThree, ok = updates[2].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(apiLabels[1].ID), updateThree.Mailbox.ID)
+	assert.Equal(t, "Y", updateThree.Mailbox.Name[len(updateThree.Mailbox.Name)-1])
+}
+
+func TestResolveLabelDiscrepancy_LabelSwapCyclic(t *testing.T) {
+	apiLabels := []proton.Label{
+		{ID: "111", Path: []string{"A"}, Type: proton.LabelTypeLabel},
+		{ID: "222", Path: []string{"B"}, Type: proton.LabelTypeLabel},
+		{ID: "333", Path: []string{"C"}, Type: proton.LabelTypeLabel},
+		{ID: "444", Path: []string{"D"}, Type: proton.LabelTypeLabel},
+	}
+
+	gluonLabels := []imap.MailboxData{
+		{RemoteID: "111", BridgeName: []string{"Labels", "D"}}, // A <- D
+		{RemoteID: "222", BridgeName: []string{"Labels", "A"}}, // B <- A
+		{RemoteID: "333", BridgeName: []string{"Labels", "B"}}, // C <- B
+		{RemoteID: "444", BridgeName: []string{"Labels", "C"}}, // D <- C
+	}
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockClient := new(mockAPIClient)
+	mockIDProvider := new(mockIDProvider)
+	mockReporter := new(mockReporter)
+
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id-1", true)
+
+	for _, mbox := range gluonLabels {
+		mockLabelProvider.
+			On("GetUserMailboxByName", mock.Anything, "gluon-id-1", mbox.BridgeName).
+			Return(mbox, nil)
+	}
+
+	for _, label := range apiLabels {
+		mockClient.
+			On("GetLabel", mock.Anything, label.ID, []proton.LabelType{proton.LabelTypeFolder, proton.LabelTypeLabel, proton.LabelTypeSystem}).
+			Return(label, nil)
+	}
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	connectors := []*imapservice.Connector{connector}
+
+	manager := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderFalse{})
+	resolver := manager.NewConflictResolver(connectors)
+
+	fn, err := resolver.ResolveConflict(context.Background(), apiLabels[0], make(map[string]bool))
+	require.NoError(t, err)
+
+	updates := fn()
+	assert.NotEmpty(t, updates)
+	assert.Equal(t, 5, len(updates))
+
+	updateOne, ok := updates[0].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(apiLabels[0].ID), updateOne.Mailbox.ID)
+	assert.Equal(t, "tmp_A", updateOne.Mailbox.Name[len(updateOne.Mailbox.Name)-1])
+
+	updateTwo, ok := updates[1].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(apiLabels[3].ID), updateTwo.Mailbox.ID)
+	assert.Equal(t, "D", updateTwo.Mailbox.Name[len(updateTwo.Mailbox.Name)-1])
+
+	updateThree, ok := updates[2].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(apiLabels[2].ID), updateThree.Mailbox.ID)
+	assert.Equal(t, "C", updateThree.Mailbox.Name[len(updateThree.Mailbox.Name)-1])
+
+	updateFour, ok := updates[3].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(apiLabels[1].ID), updateFour.Mailbox.ID)
+	assert.Equal(t, "B", updateFour.Mailbox.Name[len(updateFour.Mailbox.Name)-1])
+
+	updateFive, ok := updates[4].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(apiLabels[0].ID), updateFive.Mailbox.ID)
+	assert.Equal(t, "A", updateFive.Mailbox.Name[len(updateFive.Mailbox.Name)-1])
+}
+
+func TestResolveLabelDiscrepancy_LabelSwapCyclicWithDeletedLabel(t *testing.T) {
+	apiLabels := []proton.Label{
+		{ID: "111", Path: []string{"A"}, Type: proton.LabelTypeLabel},
+		{ID: "333", Path: []string{"C"}, Type: proton.LabelTypeLabel},
+		{ID: "444", Path: []string{"D"}, Type: proton.LabelTypeLabel},
+	}
+
+	gluonLabels := []imap.MailboxData{
+		{RemoteID: "111", BridgeName: []string{"Labels", "D"}},
+		{RemoteID: "222", BridgeName: []string{"Labels", "A"}},
+		{RemoteID: "333", BridgeName: []string{"Labels", "B"}},
+		{RemoteID: "444", BridgeName: []string{"Labels", "C"}},
+	}
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockClient := new(mockAPIClient)
+	mockIDProvider := new(mockIDProvider)
+	mockReporter := new(mockReporter)
+
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id-1", true)
+
+	for _, mbox := range gluonLabels {
+		mockLabelProvider.
+			On("GetUserMailboxByName", mock.Anything, "gluon-id-1", mbox.BridgeName).
+			Return(mbox, nil)
+	}
+
+	for _, label := range apiLabels {
+		mockClient.
+			On("GetLabel", mock.Anything, label.ID, []proton.LabelType{proton.LabelTypeFolder, proton.LabelTypeLabel, proton.LabelTypeSystem}).
+			Return(label, nil)
+	}
+	mockClient.On("GetLabel", mock.Anything, "222", []proton.LabelType{proton.LabelTypeFolder, proton.LabelTypeLabel, proton.LabelTypeSystem}).Return(proton.Label{}, proton.ErrNoSuchLabel)
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	connectors := []*imapservice.Connector{connector}
+
+	manager := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderFalse{})
+	resolver := manager.NewConflictResolver(connectors)
+
+	fn, err := resolver.ResolveConflict(context.Background(), apiLabels[2], make(map[string]bool))
+	require.NoError(t, err)
+
+	updates := fn()
+	assert.NotEmpty(t, updates)
+	assert.Equal(t, 3, len(updates))
+
+	updateOne, ok := updates[0].(*imap.MailboxDeleted)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID("222"), updateOne.MailboxID)
+
+	updateTwo, ok := updates[1].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(apiLabels[0].ID), updateTwo.Mailbox.ID)
+	assert.Equal(t, "A", updateTwo.Mailbox.Name[len(updateTwo.Mailbox.Name)-1])
+
+	updateThree, ok := updates[2].(*imap.MailboxUpdatedOrCreated)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID(apiLabels[2].ID), updateThree.Mailbox.ID)
+	assert.Equal(t, "D", updateThree.Mailbox.Name[len(updateThree.Mailbox.Name)-1])
+}
+
+func TestResolveLabelDiscrepancy_LabelSwapCyclicWithDeletedLabel_KillSwitchEnabled(t *testing.T) {
+	apiLabels := []proton.Label{
+		{ID: "111", Path: []string{"A"}, Type: proton.LabelTypeLabel},
+		{ID: "333", Path: []string{"C"}, Type: proton.LabelTypeLabel},
+		{ID: "444", Path: []string{"D"}, Type: proton.LabelTypeLabel},
+	}
+
+	gluonLabels := []imap.MailboxData{
+		{RemoteID: "111", BridgeName: []string{"Labels", "D"}},
+		{RemoteID: "222", BridgeName: []string{"Labels", "A"}},
+		{RemoteID: "333", BridgeName: []string{"Labels", "B"}},
+		{RemoteID: "444", BridgeName: []string{"Labels", "C"}},
+	}
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockClient := new(mockAPIClient)
+	mockIDProvider := new(mockIDProvider)
+	mockReporter := new(mockReporter)
+
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id-1", true)
+
+	for _, mbox := range gluonLabels {
+		mockLabelProvider.
+			On("GetUserMailboxByName", mock.Anything, "gluon-id-1", mbox.BridgeName).
+			Return(mbox, nil)
+	}
+
+	for _, label := range apiLabels {
+		mockClient.
+			On("GetLabel", mock.Anything, label.ID, []proton.LabelType{proton.LabelTypeFolder, proton.LabelTypeLabel, proton.LabelTypeSystem}).
+			Return(label, nil)
+	}
+	mockClient.On("GetLabel", mock.Anything, "222", []proton.LabelType{proton.LabelTypeFolder, proton.LabelTypeLabel, proton.LabelTypeSystem}).Return(proton.Label{}, proton.ErrNoSuchLabel)
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	connectors := []*imapservice.Connector{connector}
+
+	manager := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderTrue{})
+	resolver := manager.NewConflictResolver(connectors)
+
+	fn, err := resolver.ResolveConflict(context.Background(), apiLabels[2], make(map[string]bool))
+	require.NoError(t, err)
+
+	updates := fn()
+	assert.Empty(t, updates)
+}
+
+func TestInternalLabelConflictResolver_NoConflicts(t *testing.T) {
+	ctx := context.Background()
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockClient := new(mockAPIClient)
+	mockIDProvider := new(mockIDProvider)
+	mockReporter := new(mockReporter)
+
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id-1", true)
+
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id-1", []string{"Folders"}).
+		Return(imap.MailboxData{}, db.ErrNotFound)
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id-1", []string{"Labels"}).
+		Return(imap.MailboxData{}, db.ErrNotFound)
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	connectors := []*imapservice.Connector{connector}
+
+	manager := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderFalse{})
+	resolver := manager.NewInternalLabelConflictResolver(connectors)
+
+	apiLabels := make(map[string]proton.Label)
+	fn, err := resolver.ResolveConflict(ctx, apiLabels)
+	assert.NoError(t, err)
+
+	updates := fn()
+	assert.Empty(t, updates)
+}
+
+func TestInternalLabelConflictResolver_CorrectIDs(t *testing.T) {
+	ctx := context.Background()
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockClient := new(mockAPIClient)
+	mockIDProvider := new(mockIDProvider)
+	mockReporter := new(mockReporter)
+
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id-1", true)
+
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id-1", []string{"Folders"}).
+		Return(imap.MailboxData{RemoteID: "Folders", BridgeName: []string{"Folders"}}, nil)
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id-1", []string{"Labels"}).
+		Return(imap.MailboxData{RemoteID: "Labels", BridgeName: []string{"Labels"}}, nil)
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	connectors := []*imapservice.Connector{connector}
+
+	manager := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderFalse{})
+	resolver := manager.NewInternalLabelConflictResolver(connectors)
+
+	apiLabels := make(map[string]proton.Label)
+	fn, err := resolver.ResolveConflict(ctx, apiLabels)
+	assert.NoError(t, err)
+
+	updates := fn()
+	assert.Empty(t, updates)
+}
+
+type mockMailboxCountProvider struct {
+	mock.Mock
+}
+
+func (m *mockMailboxCountProvider) GetUserMailboxCountByInternalID(ctx context.Context, addrID string, internalID imap.InternalMailboxID) (int, error) {
+	args := m.Called(ctx, addrID, internalID)
+	return args.Int(0), args.Error(1)
+}
+
+func TestInternalLabelConflictResolver_ConflictingNonAPILabel_ZeroCount(t *testing.T) {
+	ctx := context.Background()
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockClient := new(mockAPIClient)
+	mockIDProvider := new(mockIDProvider)
+	mockReporter := new(mockReporter)
+	mockCountProvider := new(mockMailboxCountProvider)
+
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id-1", true)
+
+	// Mock mailbox fetch to return conflicting mailbox
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id-1", []string{"Folders"}).
+		Return(imap.MailboxData{RemoteID: "wrong-id", BridgeName: []string{"Folders"}, InternalID: imap.InternalMailboxID(123)}, nil)
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id-1", []string{"Labels"}).
+		Return(imap.MailboxData{}, db.ErrNotFound)
+
+	// Mock message count fetch to return 0 messages.
+	mockLabelProvider.On("GetMailboxMessageCount", mock.Anything, "gluon-id-1", imap.InternalMailboxID(123)).
+		Return(0, nil)
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	mockCountProvider.On("GetUserMailboxCountByInternalID",
+		mock.Anything,
+		"addr-1",
+		imap.InternalMailboxID(123)).
+		Return(0, nil)
+
+	connector.SetMailboxCountProviderTest(mockCountProvider)
+	connectors := []*imapservice.Connector{connector}
+
+	manager := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderFalse{})
+	resolver := manager.NewInternalLabelConflictResolver(connectors)
+
+	// API labels don't contain the conflicting label ID
+	apiLabels := make(map[string]proton.Label)
+	fn, err := resolver.ResolveConflict(ctx, apiLabels)
+	assert.NoError(t, err)
+
+	updates := fn()
+	assert.Len(t, updates, 1)
+
+	deleted, ok := updates[0].(*imap.MailboxDeletedSilent)
+	assert.True(t, ok)
+	assert.Equal(t, imap.MailboxID("wrong-id"), deleted.MailboxID)
+}
+
+func TestInternalLabelConflictResolver_ConflictingNonAPILabel_PositiveCount(t *testing.T) {
+	ctx := context.Background()
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockClient := new(mockAPIClient)
+	mockIDProvider := new(mockIDProvider)
+	mockReporter := new(mockReporter)
+	mockCountProvider := new(mockMailboxCountProvider)
+
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id-1", true)
+
+	mockReporter.On("ReportWarningWithContext", mock.Anything, mock.Anything).
+		Return(nil)
+
+	// Mock mailbox fetch to return conflicting mailbox
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id-1", []string{"Folders"}).
+		Return(imap.MailboxData{RemoteID: "wrong-id", BridgeName: []string{"Folders"}, InternalID: imap.InternalMailboxID(123)}, nil)
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id-1", []string{"Labels"}).
+		Return(imap.MailboxData{}, db.ErrNotFound)
+
+	// Mock message count fetch to return 0 messages.
+	mockLabelProvider.On("GetMailboxMessageCount", mock.Anything, "gluon-id-1", imap.InternalMailboxID(123)).
+		Return(0, nil)
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	mockCountProvider.On("GetUserMailboxCountByInternalID",
+		mock.Anything,
+		"addr-1",
+		imap.InternalMailboxID(123)).
+		Return(10, nil)
+
+	connector.SetMailboxCountProviderTest(mockCountProvider)
+	connectors := []*imapservice.Connector{connector}
+
+	manager := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderFalse{})
+	resolver := manager.NewInternalLabelConflictResolver(connectors)
+
+	// API labels don't contain the conflicting label ID
+	apiLabels := make(map[string]proton.Label)
+	fn, err := resolver.ResolveConflict(ctx, apiLabels)
+	assert.EqualError(t, err, "internal mailbox conflicting non-api label has associated messages")
+
+	updates := fn()
+	assert.Empty(t, updates, 0)
+}
+
+func TestInternalLabelConflictResolver_ConflictingAPILabelSameName(t *testing.T) {
+	ctx := context.Background()
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockClient := new(mockAPIClient)
+	mockIDProvider := new(mockIDProvider)
+	mockReporter := new(mockReporter)
+	mockCountProvider := new(mockMailboxCountProvider)
+
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id-1", true)
+
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id-1", []string{"Folders"}).
+		Return(imap.MailboxData{RemoteID: "api-label-id", BridgeName: []string{"Folders"}}, nil)
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id-1", []string{"Labels"}).
+		Return(imap.MailboxData{}, db.ErrNotFound)
+
+	mockReporter.On("ReportMessageWithContext", "Internal mailbox name conflict. Same-name mailbox is returned by API", mock.Anything).
+		Return(nil)
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	connector.SetMailboxCountProviderTest(mockCountProvider)
+	connectors := []*imapservice.Connector{connector}
+
+	manager := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderFalse{})
+	resolver := manager.NewInternalLabelConflictResolver(connectors)
+
+	// API user label with empty path.
+	apiLabels := map[string]proton.Label{
+		"api-label-id": {
+			ID:   "api-label-id",
+			Name: "Folders",
+			Path: []string{""},
+			Type: proton.LabelTypeFolder,
+		},
+	}
+
+	_, err := resolver.ResolveConflict(ctx, apiLabels)
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "API label")
+	assert.Contains(t, err.Error(), "conflicts with internal label")
+}
+
+func TestInternalLabelConflictResolver_MailboxFetchError(t *testing.T) {
+	ctx := context.Background()
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockClient := new(mockAPIClient)
+	mockIDProvider := new(mockIDProvider)
+	mockReporter := new(mockReporter)
+
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id-1", true)
+
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id-1", []string{"Folders"}).
+		Return(imap.MailboxData{}, errors.New("database connection error"))
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	connectors := []*imapservice.Connector{connector}
+
+	manager := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderFalse{})
+	resolver := manager.NewInternalLabelConflictResolver(connectors)
+
+	apiLabels := make(map[string]proton.Label)
+	_, err := resolver.ResolveConflict(ctx, apiLabels)
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "database connection error")
+}
+
+func TestNewInternalLabelConflictResolver_KillSwitchEnabled(t *testing.T) {
+	ctx := context.Background()
+
+	mockLabelProvider := new(mockLabelNameProvider)
+	mockClient := new(mockAPIClient)
+	mockIDProvider := new(mockIDProvider)
+	mockReporter := new(mockReporter)
+
+	mockIDProvider.On("GetGluonID", "addr-1").Return("gluon-id-1", true)
+
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id-1", []string{"Folders"}).
+		Return(imap.MailboxData{RemoteID: "wrong-folders-id", BridgeName: []string{"Folders"}}, nil)
+	mockLabelProvider.On("GetUserMailboxByName", mock.Anything, "gluon-id-1", []string{"Labels"}).
+		Return(imap.MailboxData{RemoteID: "wrong-labels-id", BridgeName: []string{"Labels"}}, nil)
+
+	connector := &imapservice.Connector{}
+	connector.SetAddrIDTest("addr-1")
+	connectors := []*imapservice.Connector{connector}
+
+	manager := imapservice.NewLabelConflictManager(mockLabelProvider, mockIDProvider, mockClient, mockReporter, ffProviderTrue{})
+	resolver := manager.NewInternalLabelConflictResolver(connectors)
+
+	apiLabels := map[string]proton.Label{
+		"some-api-label": {
+			ID:   "some-api-label",
+			Name: "SomeLabel",
+			Path: []string{"SomeLabel"},
+			Type: proton.LabelTypeLabel,
+		},
+	}
+
+	fn, err := resolver.ResolveConflict(ctx, apiLabels)
+	assert.NoError(t, err)
+
+	updates := fn()
+	assert.Empty(t, updates)
+}
--- a/internal/services/imapservice/connector.go
+++ b/internal/services/imapservice/connector.go
@ -45,6 +45,10 @@ import (
 	"golang.org/x/exp/slices"
 )

+type mailboxCountProvider interface {
+	GetUserMailboxCountByInternalID(ctx context.Context, addrID string, internalID imap.InternalMailboxID) (int, error)
+}
+
 // Connector contains all IMAP state required to satisfy sync and or imap queries.
 type Connector struct {
 	addrID      string
@ -67,6 +71,8 @@ type Connector struct {

 	sharedCache *SharedCache
 	syncState   *SyncState
+
+	mailboxCountProvider mailboxCountProvider
 }

 var errNoSenderAddressMatch = errors.New("no matching sender found in address list")
@ -82,6 +88,7 @@ func NewConnector(
 	reporter reporter.Reporter,
 	showAllMail bool,
 	syncState *SyncState,
+	mailboxCountProvider mailboxCountProvider,
 ) *Connector {
 	userID := identityState.UserID()

@ -115,6 +122,8 @@ func NewConnector(

 		sharedCache: NewSharedCached(),
 		syncState:   syncState,
+
+		mailboxCountProvider: mailboxCountProvider,
 	}
 }

@ -257,7 +266,7 @@ func (s *Connector) DeleteMailbox(ctx context.Context, _ connector.IMAPStateWrit
 	wLabels := s.labels.Write()
 	defer wLabels.Close()

-	wLabels.Delete(string(mboxID))
+	wLabels.Delete(string(mboxID), "connectorDeleteMailbox")

 	return nil
 }
@ -555,7 +564,7 @@ func (s *Connector) createLabel(ctx context.Context, name []string) (imap.Mailbo
 	wLabels := s.labels.Write()
 	defer wLabels.Close()

-	wLabels.SetLabel(label.ID, label)
+	wLabels.SetLabel(label.ID, label, "connectorCreateLabel")

 	return toIMAPMailbox(label, s.flags, s.permFlags, s.attrs), nil
 }
@ -593,7 +602,7 @@ func (s *Connector) createFolder(ctx context.Context, name []string) (imap.Mailb
 	}

 	// Add label to list so subsequent sub folder create requests work correct.
-	wLabels.SetLabel(label.ID, label)
+	wLabels.SetLabel(label.ID, label, "connectorCreateFolder")

 	return toIMAPMailbox(label, s.flags, s.permFlags, s.attrs), nil
 }
@ -619,7 +628,7 @@ func (s *Connector) updateLabel(ctx context.Context, labelID imap.MailboxID, nam
 	wLabels := s.labels.Write()
 	defer wLabels.Close()

-	wLabels.SetLabel(label.ID, update)
+	wLabels.SetLabel(label.ID, update, "connectorUpdateLabel")

 	return nil
 }
@ -660,7 +669,7 @@ func (s *Connector) updateFolder(ctx context.Context, labelID imap.MailboxID, na
 		return err
 	}

-	wLabels.SetLabel(label.ID, update)
+	wLabels.SetLabel(label.ID, update, "connectorUpdateFolder")

 	return nil
 }
@ -680,7 +689,7 @@ func (s *Connector) importMessage(
 	}

 	isDraft := slices.Contains(labelIDs, proton.DraftsLabel)
-	addr, err := s.getImportAddress(p, isDraft)
+	addr, err := getImportAddress(p, isDraft, s.addrID, s)
 	if err != nil {
 		return imap.Message{}, nil, err
 	}
@ -800,8 +809,10 @@ func (s *Connector) createDraftWithParser(ctx context.Context, parser *parser.Pa
 	return draft, nil
 }

-func (s *Connector) publishUpdate(_ context.Context, update imap.Update) {
-	s.updateCh.Enqueue(update)
+func (s *Connector) publishUpdate(_ context.Context, updates ...imap.Update) {
+	for _, update := range updates {
+		s.updateCh.Enqueue(update)
+	}
 }

 func fixGODT3003Labels(
@ -871,45 +882,6 @@ func equalAddresses(a, b string) bool {
 	return strings.EqualFold(stripPlusAlias(a), stripPlusAlias(b))
 }

-func (s *Connector) getImportAddress(p *parser.Parser, isDraft bool) (proton.Address, error) {
-	// addr is primary for combined mode or active for split mode
-	address, ok := s.identityState.GetAddress(s.addrID)
-	if !ok {
-		return proton.Address{}, errors.New("could not find account address")
-	}
-
-	inCombinedMode := s.addressMode == usertypes.AddressModeCombined
-	if !inCombinedMode {
-		return address, nil
-	}
-
-	senderAddr, err := s.getSenderProtonAddress(p)
-	if err != nil {
-		if !errors.Is(err, errNoSenderAddressMatch) {
-			s.log.WithError(err).Warn("Could not get import address")
-		}
-
-		// We did not find a match, so we use the default address.
-		return address, nil
-	}
-
-	if senderAddr.ID == address.ID {
-		return address, nil
-	}
-
-	// GODT-3185 / BRIDGE-120 In combined mode, in certain cases we adapt the address used for encryption.
-	// - draft with non-default address in combined mode: using sender address
-	// - import with non-default address in combined mode: using sender address
-	// - import with non-default disabled address in combined mode: using sender address
-
-	isSenderAddressDisabled := (!bool(senderAddr.Send)) || (senderAddr.Status != proton.AddressStatusEnabled)
-	if isDraft && isSenderAddressDisabled {
-		return address, nil
-	}
-
-	return senderAddr, nil
-}
-
 func (s *Connector) getSenderProtonAddress(p *parser.Parser) (proton.Address, error) {
 	// Step 1: extract sender email address from message
 	if (p == nil) || (p.Root() == nil) || (p.Root().Header.Len() == 0) {
@ -942,3 +914,16 @@ func (s *Connector) getSenderProtonAddress(p *parser.Parser) (proton.Address, er

 	return addressList[index], nil
 }
+
+func (s *Connector) SetAddrIDTest(addrID string) {
+	s.addrID = addrID
+}
+
+func (s *Connector) GetMailboxMessageCount(ctx context.Context, mailboxInternalID imap.InternalMailboxID) (int, error) {
+	return s.mailboxCountProvider.GetUserMailboxCountByInternalID(ctx, s.addrID, mailboxInternalID)
+}
+
+// SetMailboxCountProviderTest - sets the relevant provider. Should only be used for testing.
+func (s *Connector) SetMailboxCountProviderTest(provider mailboxCountProvider) {
+	s.mailboxCountProvider = provider
+}
--- a/internal/services/imapservice/connector_test.go
+++ b/internal/services/imapservice/connector_test.go
@ -43,7 +43,7 @@ func TestFixGODT3003Labels(t *testing.T) {
 		Path:     []string{"bar", "Foo"},
 		Color:    "",
 		Type:     proton.LabelTypeFolder,
-	})
+	}, "")

 	wr.SetLabel("0", proton.Label{
 		ID:       "0",
@ -52,7 +52,7 @@ func TestFixGODT3003Labels(t *testing.T) {
 		Path:     []string{"Inbox"},
 		Color:    "",
 		Type:     proton.LabelTypeSystem,
-	})
+	}, "")

 	wr.SetLabel("bar", proton.Label{
 		ID:       "bar",
@ -61,7 +61,7 @@ func TestFixGODT3003Labels(t *testing.T) {
 		Path:     []string{"bar"},
 		Color:    "",
 		Type:     proton.LabelTypeFolder,
-	})
+	}, "")

 	wr.SetLabel("my_label", proton.Label{
 		ID:       "my_label",
@ -70,7 +70,7 @@ func TestFixGODT3003Labels(t *testing.T) {
 		Path:     []string{"MyLabel"},
 		Color:    "",
 		Type:     proton.LabelTypeLabel,
-	})
+	}, "")

 	wr.SetLabel("my_label2", proton.Label{
 		ID:       "my_label2",
@ -79,7 +79,7 @@ func TestFixGODT3003Labels(t *testing.T) {
 		Path:     []string{labelPrefix, "MyLabel2"},
 		Color:    "",
 		Type:     proton.LabelTypeLabel,
-	})
+	}, "")
 	wr.Close()

 	mboxs := []imap.MailboxNoAttrib{
@ -133,7 +133,7 @@ func TestFixGODT3003Labels_Noop(t *testing.T) {
 		Path:     []string{folderPrefix, "bar", "Foo"},
 		Color:    "",
 		Type:     proton.LabelTypeFolder,
-	})
+	}, "")

 	wr.SetLabel("0", proton.Label{
 		ID:       "0",
@ -142,7 +142,7 @@ func TestFixGODT3003Labels_Noop(t *testing.T) {
 		Path:     []string{"Inbox"},
 		Color:    "",
 		Type:     proton.LabelTypeSystem,
-	})
+	}, "")

 	wr.SetLabel("bar", proton.Label{
 		ID:       "bar",
@ -151,7 +151,7 @@ func TestFixGODT3003Labels_Noop(t *testing.T) {
 		Path:     []string{folderPrefix, "bar"},
 		Color:    "",
 		Type:     proton.LabelTypeFolder,
-	})
+	}, "")

 	wr.SetLabel("my_label", proton.Label{
 		ID:       "my_label",
@ -160,7 +160,7 @@ func TestFixGODT3003Labels_Noop(t *testing.T) {
 		Path:     []string{labelPrefix, "MyLabel"},
 		Color:    "",
 		Type:     proton.LabelTypeLabel,
-	})
+	}, "")

 	wr.SetLabel("my_label2", proton.Label{
 		ID:       "my_label2",
@ -169,7 +169,7 @@ func TestFixGODT3003Labels_Noop(t *testing.T) {
 		Path:     []string{labelPrefix, "MyLabel2"},
 		Color:    "",
 		Type:     proton.LabelTypeLabel,
-	})
+	}, "")
 	wr.Close()

 	mboxs := []imap.MailboxNoAttrib{
--- a/internal/services/imapservice/imap_updates.go
+++ b/internal/services/imapservice/imap_updates.go
@ -102,6 +102,16 @@ func newMailboxCreatedUpdate(labelID imap.MailboxID, labelName []string) *imap.M
 	})
 }

+func newMailboxUpdatedOrCreated(labelID imap.MailboxID, labelName []string) *imap.MailboxUpdatedOrCreated {
+	return imap.NewMailboxUpdatedOrCreated(imap.Mailbox{
+		ID:             labelID,
+		Name:           labelName,
+		Flags:          defaultMailboxFlags(),
+		PermanentFlags: defaultMailboxPermanentFlags(),
+		Attributes:     imap.NewFlagSet(),
+	})
+}
+
 func GetMailboxName(label proton.Label) []string {
 	var name []string

@ -112,9 +122,10 @@ func GetMailboxName(label proton.Label) []string {
 	case proton.LabelTypeLabel:
 		name = append([]string{labelPrefix}, label.Path...)

-	case proton.LabelTypeContactGroup:
-		fallthrough
 	case proton.LabelTypeSystem:
+		name = []string{label.Name}
+
+	case proton.LabelTypeContactGroup:
 		fallthrough
 	default:
 		name = label.Path
@ -122,3 +133,12 @@ func GetMailboxName(label proton.Label) []string {

 	return name
 }
+
+func nameWithTempPrefix(path []string) []string {
+	path[len(path)-1] = "tmp_" + path[len(path)-1]
+	return path
+}
+
+func getMailboxNameWithTempPrefix(label proton.Label) []string {
+	return nameWithTempPrefix(GetMailboxName(label))
+}
--- a/internal/services/imapservice/labelchecker.go
+++ b/internal/services/imapservice/labelchecker.go
@ -0,0 +1,223 @@
+// Copyright (c) 2025 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package imapservice
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/ProtonMail/gluon/db"
+	"github.com/ProtonMail/gluon/imap"
+	"github.com/ProtonMail/gluon/reporter"
+	"github.com/ProtonMail/go-proton-api"
+	"github.com/ProtonMail/proton-bridge/v3/pkg/algo"
+	"github.com/sirupsen/logrus"
+)
+
+type labelDiscrepancyType int
+
+const (
+	discrepancyInternal labelDiscrepancyType = iota
+	discrepancySystem
+	discrepancyUser
+)
+
+func (t labelDiscrepancyType) String() string {
+	switch t {
+	case discrepancyInternal:
+		return "internal"
+	case discrepancySystem:
+		return "system"
+	case discrepancyUser:
+		return "user"
+	default:
+		return "unknown"
+	}
+}
+
+type labelDiscrepancy struct {
+	labelName            string
+	labelPath            string
+	labelPathParsed      string
+	labelID              string
+	conflictingLabelName string
+	conflictingLabelID   string
+	Type                 labelDiscrepancyType
+}
+
+func joinStrings(input []string) string {
+	return strings.Join(input, "/")
+}
+
+func newLabelDiscrepancy(label proton.Label, mbox imap.MailboxData, dType labelDiscrepancyType) labelDiscrepancy {
+	discrepancy := labelDiscrepancy{
+		labelName:          label.Name,
+		labelID:            label.ID,
+		conflictingLabelID: mbox.RemoteID,
+		Type:               dType,
+	}
+
+	if dType == discrepancyUser {
+		discrepancy.labelName = algo.HashBase64SHA256(label.Name)
+		discrepancy.labelPath = algo.HashBase64SHA256(joinStrings(label.Path))
+		discrepancy.labelPathParsed = algo.HashBase64SHA256(joinStrings(GetMailboxName(label)))
+		discrepancy.conflictingLabelName = algo.HashBase64SHA256(joinStrings(mbox.BridgeName))
+	} else {
+		discrepancy.labelName = label.Name
+		discrepancy.labelPath = joinStrings(label.Path)
+		discrepancy.labelPathParsed = joinStrings(GetMailboxName(label))
+		discrepancy.conflictingLabelName = joinStrings(mbox.BridgeName)
+	}
+
+	return discrepancy
+}
+
+func discrepanciesToContext(discrepancies []labelDiscrepancy) reporter.Context {
+	ctx := make(reporter.Context)
+
+	for i, d := range discrepancies {
+		prefix := fmt.Sprintf("discrepancy_%d_", i)
+
+		ctx[prefix+"type"] = d.Type.String()
+		ctx[prefix+"label_id"] = d.labelID
+		ctx[prefix+"label_name"] = d.labelName
+		ctx[prefix+"label_path"] = d.labelPath
+		ctx[prefix+"label_path_parsed"] = d.labelPathParsed
+		ctx[prefix+"conflicting_label_name"] = d.conflictingLabelName
+		ctx[prefix+"conflicting_label_id"] = d.conflictingLabelID
+	}
+
+	ctx["discrepancy_count"] = len(discrepancies)
+	return ctx
+}
+
+type ConnectorGetter interface {
+	getConnectors() []*Connector
+}
+
+type LabelConflictChecker struct {
+	gluonLabelNameProvider GluonLabelNameProvider
+	gluonIDProvider        gluonIDProvider
+	connectorGetter        ConnectorGetter
+	reporter               reporter.Reporter
+	logger                 *logrus.Entry
+}
+
+func NewConflictChecker(connectorGetter ConnectorGetter, reporter reporter.Reporter, provider gluonIDProvider, nameProvider GluonLabelNameProvider) *LabelConflictChecker {
+	return &LabelConflictChecker{
+		gluonLabelNameProvider: nameProvider,
+		gluonIDProvider:        provider,
+		connectorGetter:        connectorGetter,
+		reporter:               reporter,
+		logger: logrus.WithFields(logrus.Fields{
+			"pkg": "imapservice/labelConflictChecker",
+		}),
+	}
+}
+
+func (c *LabelConflictChecker) getFn() mailboxFetcherFn {
+	connectors := c.connectorGetter.getConnectors()
+
+	return func(ctx context.Context, label proton.Label) (imap.MailboxData, error) {
+		for _, updateCh := range connectors {
+			addrID, ok := c.gluonIDProvider.GetGluonID(updateCh.addrID)
+			if !ok {
+				continue
+			}
+			return c.gluonLabelNameProvider.GetUserMailboxByName(ctx, addrID, GetMailboxName(label))
+		}
+		return imap.MailboxData{}, errors.New("no gluon connectors found")
+	}
+}
+
+func (c *LabelConflictChecker) CheckAndReportConflicts(ctx context.Context, labels map[string]proton.Label) error {
+	labelDiscrepancies, err := c.checkConflicts(ctx, labels, c.getFn())
+	if err != nil {
+		return err
+	}
+
+	if len(labelDiscrepancies) == 0 {
+		return nil
+	}
+
+	reporterCtx := discrepanciesToContext(labelDiscrepancies)
+	if err := c.reporter.ReportMessageWithContext("Found label conflicts on Bridge start", reporterCtx); err != nil {
+		c.logger.WithError(err).Error("Failed to report label conflicts to Sentry")
+	}
+
+	return nil
+}
+
+func (c *LabelConflictChecker) checkConflicts(ctx context.Context, labels map[string]proton.Label, mboxFetch mailboxFetcherFn) ([]labelDiscrepancy, error) {
+	discrepancies := []labelDiscrepancy{}
+
+	// Verify bridge internal mailboxes.
+	for _, prefix := range []string{folderPrefix, labelPrefix} {
+		label := proton.Label{
+			Path: []string{prefix},
+			ID:   prefix,
+			Name: prefix,
+		}
+
+		mbox, err := mboxFetch(ctx, label)
+		if err != nil {
+			if db.IsErrNotFound(err) {
+				continue
+			}
+			return nil, err
+		}
+
+		if mbox.RemoteID != label.ID {
+			discrepancies = append(discrepancies, newLabelDiscrepancy(label, mbox, discrepancyInternal))
+		}
+	}
+
+	// Verify system and user mailboxes.
+	for _, label := range labels {
+		if !WantLabel(label) {
+			continue
+		}
+
+		mbox, err := mboxFetch(ctx, label)
+		if err != nil {
+			if db.IsErrNotFound(err) {
+				continue
+			}
+			return nil, err
+		}
+
+		if mbox.RemoteID != label.ID {
+			var dType labelDiscrepancyType
+			switch label.Type {
+			case proton.LabelTypeSystem:
+				dType = discrepancySystem
+			case proton.LabelTypeFolder, proton.LabelTypeLabel:
+				dType = discrepancyUser
+			case proton.LabelTypeContactGroup:
+				fallthrough
+			default:
+				dType = discrepancySystem
+			}
+			discrepancies = append(discrepancies, newLabelDiscrepancy(label, mbox, dType))
+		}
+	}
+
+	return discrepancies, nil
+}
--- a/internal/services/imapservice/server_manager.go
+++ b/internal/services/imapservice/server_manager.go
@ -21,6 +21,7 @@ import (
 	"context"

 	"github.com/ProtonMail/gluon/connector"
+	"github.com/ProtonMail/gluon/imap"
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/syncservice"
 )

@ -34,6 +35,16 @@ type IMAPServerManager interface {
 	) error

 	RemoveIMAPUser(ctx context.Context, deleteData bool, provider GluonIDProvider, addrID ...string) error
+
+	LogRemoteLabelIDs(ctx context.Context, provider GluonIDProvider, addrID ...string) error
+
+	GetUserMailboxByName(ctx context.Context, addrID string, mailboxName []string) (imap.MailboxData, error)
+
+	GetUserMailboxCountByInternalID(ctx context.Context, addrID string, internalID imap.InternalMailboxID) (int, error)
+
+	GetOpenIMAPSessionCount() int
+
+	GetRollingIMAPConnectionCount() int
 }

 type NullIMAPServerManager struct{}
@ -57,6 +68,30 @@ func (n NullIMAPServerManager) RemoveIMAPUser(
 	return nil
 }

+func (n NullIMAPServerManager) LogRemoteLabelIDs(
+	_ context.Context,
+	_ GluonIDProvider,
+	_ ...string,
+) error {
+	return nil
+}
+
+func (n NullIMAPServerManager) GetUserMailboxByName(_ context.Context, _ string, _ []string) (imap.MailboxData, error) {
+	return imap.MailboxData{}, nil
+}
+
+func (n NullIMAPServerManager) GetUserMailboxCountByInternalID(_ context.Context, _ string, _ imap.InternalMailboxID) (int, error) {
+	return 0, nil
+}
+
+func (n NullIMAPServerManager) GetOpenIMAPSessionCount() int {
+	return 0
+}
+
+func (n NullIMAPServerManager) GetRollingIMAPConnectionCount() int {
+	return 0
+}
+
 func NewNullIMAPServerManager() *NullIMAPServerManager {
 	return &NullIMAPServerManager{}
 }
--- a/internal/services/imapservice/service.go
+++ b/internal/services/imapservice/service.go
@ -36,6 +36,7 @@ import (
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/syncservice"
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/userevents"
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/useridentity"
+	"github.com/ProtonMail/proton-bridge/v3/internal/unleash"
 	"github.com/ProtonMail/proton-bridge/v3/internal/usertypes"
 	"github.com/ProtonMail/proton-bridge/v3/pkg/cpc"
 	"github.com/sirupsen/logrus"
@ -91,7 +92,9 @@ type Service struct {
 	lastHandledEventID string
 	isSyncing          atomic.Bool

-	observabilitySender observability.Sender
+	observabilitySender  observability.Sender
+	labelConflictManager *LabelConflictManager
+	LabelConflictChecker *LabelConflictChecker
 }

 func NewService(
@ -112,6 +115,7 @@ func NewService(
 	maxSyncMemory uint64,
 	showAllMail bool,
 	observabilitySender observability.Sender,
+	featureFlagProvider unleash.FeatureFlagValueProvider,
 ) *Service {
 	subscriberName := fmt.Sprintf("imap-%v", identityState.User.ID)

@ -121,11 +125,12 @@ func NewService(
 	})
 	rwIdentity := newRWIdentity(identityState, bridgePassProvider, keyPassProvider)

-	syncUpdateApplier := NewSyncUpdateApplier()
+	labelConflictManager := NewLabelConflictManager(serverManager, gluonIDProvider, client, reporter, featureFlagProvider)
+	syncUpdateApplier := NewSyncUpdateApplier(labelConflictManager)
 	syncMessageBuilder := NewSyncMessageBuilder(rwIdentity)
 	syncReporter := newSyncReporter(identityState.User.ID, eventPublisher, time.Second)

-	return &Service{
+	service := &Service{
 		cpc:           cpc.NewCPC(),
 		client:        client,
 		log:           log,
@ -156,8 +161,12 @@ func NewService(
 		syncReporter:       syncReporter,
 		syncConfigPath:     GetSyncConfigPath(syncConfigDir, identityState.User.ID),

-		observabilitySender: observabilitySender,
+		observabilitySender:  observabilitySender,
+		labelConflictManager: labelConflictManager,
 	}
+
+	service.LabelConflictChecker = NewConflictChecker(service, reporter, gluonIDProvider, serverManager)
+	return service
 }

 func (s *Service) Start(
@ -176,7 +185,14 @@ func (s *Service) Start(
 		s.syncStateProvider = syncStateProvider
 	}

-	s.syncHandler = syncservice.NewHandler(syncRegulator, s.client, s.identityState.UserID(), s.syncStateProvider, s.log, s.panicHandler)
+	s.syncHandler = syncservice.NewHandler(
+		syncRegulator,
+		s.client,
+		s.identityState.UserID(),
+		s.syncStateProvider,
+		s.log,
+		s.panicHandler,
+		s.reporter)

 	// Get user labels
 	apiLabels, err := s.client.GetLabels(ctx, proton.LabelTypeSystem, proton.LabelTypeFolder, proton.LabelTypeLabel)
@ -355,6 +371,12 @@ func (s *Service) run(ctx context.Context) { //nolint gocyclo

 			case *onBadEventReq:
 				s.log.Debug("Bad Event Request")
+				// // Log remote label IDs stored in the local labelMap.
+				s.labels.LogLabels()
+				// Log the remote label IDs store in Gluon.
+				if err := s.logRemoteMailboxIDsFromServer(ctx, s.connectors); err != nil {
+					s.log.Warnf("Could not obtain remote mailbox IDs from server: %v", err)
+				}
 				err := s.removeConnectorsFromServer(ctx, s.connectors, false)
 				req.Reply(ctx, nil, err)

@ -518,6 +540,7 @@ func (s *Service) buildConnectors() (map[string]*Connector, error) {
 			s.reporter,
 			s.showAllMail,
 			s.syncStateProvider,
+			s.serverManager,
 		)

 		return connectors, nil
@ -535,6 +558,7 @@ func (s *Service) buildConnectors() (map[string]*Connector, error) {
 			s.reporter,
 			s.showAllMail,
 			s.syncStateProvider,
+			s.serverManager,
 		)
 	}

@ -572,6 +596,16 @@ func (s *Service) addConnectorsToServer(ctx context.Context, connectors map[stri
 	return nil
 }

+func (s *Service) logRemoteMailboxIDsFromServer(ctx context.Context, connectors map[string]*Connector) error {
+	addrIDs := make([]string, 0, len(connectors))
+
+	for _, c := range connectors {
+		addrIDs = append(addrIDs, c.addrID)
+	}
+
+	return s.serverManager.LogRemoteLabelIDs(ctx, s.gluonIDProvider, addrIDs...)
+}
+
 func (s *Service) removeConnectorsFromServer(ctx context.Context, connectors map[string]*Connector, deleteData bool) error {
 	addrIDs := make([]string, 0, len(connectors))

@ -635,7 +669,7 @@ func (s *Service) setShowAllMail(v bool) {

 func (s *Service) startSyncing() {
 	s.isSyncing.Store(true)
-	s.syncHandler.Execute(s.syncReporter, s.labels.GetLabelMap(), s.syncUpdateApplier, s.syncMessageBuilder, syncservice.DefaultRetryCoolDown)
+	s.syncHandler.Execute(s.syncReporter, s.labels.GetLabelMap(), s.syncUpdateApplier, s.syncMessageBuilder, syncservice.DefaultRetryCoolDown, s.LabelConflictChecker)
 }

 func (s *Service) cancelSync() {
@ -643,6 +677,10 @@ func (s *Service) cancelSync() {
 	s.isSyncing.Store(false)
 }

+func (s *Service) getConnectors() []*Connector {
+	return maps.Values(s.connectors)
+}
+
 type resyncReq struct{}

 type getLabelsReq struct{}
--- a/internal/services/imapservice/service_address_events.go
+++ b/internal/services/imapservice/service_address_events.go
@ -157,6 +157,7 @@ func addNewAddressSplitMode(ctx context.Context, s *Service, addrID string) erro
 		s.reporter,
 		s.showAllMail,
 		s.syncStateProvider,
+		s.serverManager,
 	)

 	if err := s.serverManager.AddIMAPUser(ctx, connector, connector.addrID, s.gluonIDProvider, s.syncStateProvider); err != nil {
@ -165,7 +166,7 @@ func addNewAddressSplitMode(ctx context.Context, s *Service, addrID string) erro

 	s.connectors[connector.addrID] = connector

-	updates, err := syncLabels(ctx, s.labels.GetLabelMap(), []*Connector{connector})
+	updates, err := syncLabels(ctx, s.labels.GetLabelMap(), []*Connector{connector}, s.labelConflictManager)
 	if err != nil {
 		return fmt.Errorf("failed to create labels updates for new address: %w", err)
 	}
--- a/internal/services/imapservice/service_label_events.go
+++ b/internal/services/imapservice/service_label_events.go
@ -42,7 +42,10 @@ func (s *Service) HandleLabelEvents(ctx context.Context, events []proton.LabelEv
 				continue
 			}

-			updates := onLabelCreated(ctx, s, event)
+			updates, err := onLabelCreated(ctx, s, event)
+			if err != nil {
+				return fmt.Errorf("failed to handle create label event: %w", err)
+			}

 			if err := waitOnIMAPUpdates(ctx, updates); err != nil {
 				return err
@ -74,8 +77,8 @@ func (s *Service) HandleLabelEvents(ctx context.Context, events []proton.LabelEv
 	return nil
 }

-func onLabelCreated(ctx context.Context, s *Service, event proton.LabelEvent) []imap.Update {
-	updates := make([]imap.Update, 0, len(s.connectors))
+func onLabelCreated(ctx context.Context, s *Service, event proton.LabelEvent) ([]imap.Update, error) {
+	updates := []imap.Update{}

 	s.log.WithFields(logrus.Fields{
 		"labelID": event.ID,
@ -85,9 +88,19 @@ func onLabelCreated(ctx context.Context, s *Service, event proton.LabelEvent) []
 	wr := s.labels.Write()
 	defer wr.Close()

-	wr.SetLabel(event.Label.ID, event.Label)
+	wr.SetLabel(event.Label.ID, event.Label, "onLabelCreated")
+
+	labelConflictResolver := s.labelConflictManager.NewConflictResolver(maps.Values(s.connectors))
+	conflictUpdatesGenerator, err := labelConflictResolver.ResolveConflict(ctx, event.Label, make(map[string]bool))
+	if err != nil {
+		return updates, err
+	}

 	for _, updateCh := range maps.Values(s.connectors) {
+		conflictUpdates := conflictUpdatesGenerator()
+		updateCh.publishUpdate(ctx, conflictUpdates...)
+		updates = append(updates, conflictUpdates...)
+
 		update := newMailboxCreatedUpdate(imap.MailboxID(event.ID), GetMailboxName(event.Label))
 		updateCh.publishUpdate(ctx, update)
 		updates = append(updates, update)
@ -99,7 +112,7 @@ func onLabelCreated(ctx context.Context, s *Service, event proton.LabelEvent) []
 		Name:    event.Label.Name,
 	})

-	return updates
+	return updates, nil
 }

 func onLabelUpdated(ctx context.Context, s *Service, event proton.LabelEvent) ([]imap.Update, error) {
@ -121,7 +134,7 @@ func onLabelUpdated(ctx context.Context, s *Service, event proton.LabelEvent) ([

 		// Only update the label if it exists; we don't want to create it as a client may have just deleted it.
 		if _, ok := wr.GetLabel(label.ID); ok {
-			wr.SetLabel(label.ID, event.Label)
+			wr.SetLabel(label.ID, event.Label, "onLabelUpdatedLabelEventID")
 		}

 		// API doesn't notify us that the path has changed. We need to fetch it again.
@ -134,10 +147,21 @@ func onLabelUpdated(ctx context.Context, s *Service, event proton.LabelEvent) ([
 		}

 		// Update the label in the map.
-		wr.SetLabel(apiLabel.ID, apiLabel)
+		wr.SetLabel(apiLabel.ID, apiLabel, "onLabelUpdatedApiID")
+
+		// Resolve potential conflicts
+		labelConflictResolver := s.labelConflictManager.NewConflictResolver(maps.Values(s.connectors))
+		conflictUpdatesGenerator, err := labelConflictResolver.ResolveConflict(ctx, apiLabel, make(map[string]bool))
+		if err != nil {
+			return updates, err
+		}

 		// Notify the IMAP clients.
 		for _, updateCh := range maps.Values(s.connectors) {
+			conflictUpdates := conflictUpdatesGenerator()
+			updateCh.publishUpdate(ctx, conflictUpdates...)
+			updates = append(updates, conflictUpdates...)
+
 			update := imap.NewMailboxUpdated(
 				imap.MailboxID(apiLabel.ID),
 				GetMailboxName(apiLabel),
@ -176,7 +200,7 @@ func onLabelDeleted(ctx context.Context, s *Service, event proton.LabelEvent) []
 	wr := s.labels.Write()
 	wr.Close()

-	wr.Delete(event.ID)
+	wr.Delete(event.ID, "onLabelDeleted")

 	s.eventPublisher.PublishEvent(ctx, events.UserLabelDeleted{
 		UserID:  s.identityState.UserID(),
--- a/internal/services/imapservice/service_message_events.go
+++ b/internal/services/imapservice/service_message_events.go
@ -256,8 +256,8 @@ func onMessageUpdateDraftOrSent(ctx context.Context, s *Service, event proton.Me
 			res.update.Literal,
 			res.update.MailboxIDs,
 			res.update.ParsedMessage,
-			true, // Is the message doesn't exist, silently create it.
-			false,
+			true,       // Is the message doesn't exist, silently create it.
+			duringSync, // Ignore unknown labelIDs during sync.
 		)

 		didPublish, err := safePublishMessageUpdate(ctx, s, full.AddressID, update, duringSync)
--- a/internal/services/imapservice/service_sync_events.go
+++ b/internal/services/imapservice/service_sync_events.go
@ -113,7 +113,7 @@ func (s syncMessageEventHandler) HandleMessageEvents(ctx context.Context, events
 			if err := waitOnIMAPUpdates(ctx, updates); gluon.IsNoSuchMessage(err) {
 				logrus.WithError(err).Error("Failed to handle update message event in gluon, will try creating it (sync)")

-				updates, err := onMessageCreated(ctx, s.service, event.Message, false, true)
+				updates, err := onMessageCreated(ctx, s.service, event.Message, true, true)
 				if err != nil {
 					s.service.observabilitySender.AddDistinctMetrics(
 						observability.SyncError,
--- a/internal/services/imapservice/shared_labels.go
+++ b/internal/services/imapservice/shared_labels.go
@ -22,6 +22,8 @@ import (

 	"github.com/ProtonMail/go-proton-api"
 	"github.com/ProtonMail/proton-bridge/v3/internal/usertypes"
+	"github.com/bradenaw/juniper/xslices"
+	"github.com/sirupsen/logrus"
 	"golang.org/x/exp/maps"
 )

@ -42,8 +44,8 @@ type labelsRead interface {

 type labelsWrite interface {
 	labelsRead
-	SetLabel(id string, label proton.Label)
-	Delete(id string)
+	SetLabel(id string, label proton.Label, actionSource string)
+	Delete(id string, actionSource string)
 }

 type rwLabels struct {
@ -51,6 +53,22 @@ type rwLabels struct {
 	labels labelMap
 }

+func (r *rwLabels) LogLabels() {
+	r.lock.RLock()
+	defer r.lock.RUnlock()
+
+	remoteLabelIDs := make([]string, len(r.labels))
+	i := 0
+	for labelID := range r.labels {
+		remoteLabelIDs[i] = labelID
+		i++
+	}
+
+	logrus.WithFields(logrus.Fields{
+		"remoteLabelIDs": remoteLabelIDs,
+	}).Debug("Logging remote label IDs stored in labelMap")
+}
+
 func (r *rwLabels) Read() labelsRead {
 	r.lock.RLock()
 	return &rwLabelsRead{rw: r}
@ -75,6 +93,15 @@ func (r *rwLabels) SetLabels(labels []proton.Label) {
 	r.lock.Lock()
 	defer r.lock.Unlock()

+	labelIDs := xslices.Map(labels, func(label proton.Label) string {
+		return label.ID
+	})
+
+	logrus.WithFields(logrus.Fields{
+		"pkg":      "rwLabels",
+		"labelIDs": labelIDs,
+	}).Info("Setting labels")
+
 	r.labels = usertypes.GroupBy(labels, func(label proton.Label) string { return label.ID })
 }

@ -123,10 +150,20 @@ func (r rwLabelsWrite) GetLabels() []proton.Label {
 	return r.rw.getLabelsUnsafe()
 }

-func (r rwLabelsWrite) SetLabel(id string, label proton.Label) {
+func (r rwLabelsWrite) SetLabel(id string, label proton.Label, actionSource string) {
+	logAction("SetLabel", actionSource, label.ID)
 	r.rw.labels[id] = label
 }

-func (r rwLabelsWrite) Delete(id string) {
+func (r rwLabelsWrite) Delete(id string, actionSource string) {
+	logAction("Delete", actionSource, id)
 	delete(r.rw.labels, id)
 }
+
+func logAction(actionType, actionSource, labelID string) {
+	logrus.WithFields(logrus.Fields{
+		"pkg":          "rwLabelsWrite",
+		"actionSource": actionSource,
+		"labelID":      labelID,
+	}).Debug(actionType)
+}
--- a/internal/services/imapservice/sync_update_applier.go
+++ b/internal/services/imapservice/sync_update_applier.go
@ -31,8 +31,9 @@ import (
 )

 type SyncUpdateApplier struct {
-	requestCh chan updateRequest
-	replyCh   chan updateReply
+	requestCh            chan updateRequest
+	replyCh              chan updateReply
+	labelConflictManager *LabelConflictManager
 }

 type updateReply struct {
@ -42,10 +43,11 @@ type updateReply struct {

 type updateRequest = func(ctx context.Context, mode usertypes.AddressMode, connectors map[string]*Connector) ([]imap.Update, error)

-func NewSyncUpdateApplier() *SyncUpdateApplier {
+func NewSyncUpdateApplier(labelConflictManager *LabelConflictManager) *SyncUpdateApplier {
 	return &SyncUpdateApplier{
-		requestCh: make(chan updateRequest),
-		replyCh:   make(chan updateReply),
+		requestCh:            make(chan updateRequest),
+		replyCh:              make(chan updateReply),
+		labelConflictManager: labelConflictManager,
 	}
 }

@ -111,42 +113,9 @@ func (s *SyncUpdateApplier) ApplySyncUpdates(ctx context.Context, updates []sync
 	return nil
 }

-func (s *SyncUpdateApplier) SyncSystemLabelsOnly(ctx context.Context, labels map[string]proton.Label) error {
-	request := func(ctx context.Context, _ usertypes.AddressMode, connectors map[string]*Connector) ([]imap.Update, error) {
-		updates := make([]imap.Update, 0, len(labels)*len(connectors))
-		for _, label := range labels {
-			if !WantLabel(label) {
-				continue
-			}
-
-			if label.Type != proton.LabelTypeSystem {
-				continue
-			}
-
-			for _, c := range connectors {
-				update := newSystemMailboxCreatedUpdate(imap.MailboxID(label.ID), label.Name)
-				updates = append(updates, update)
-				c.publishUpdate(ctx, update)
-			}
-		}
-		return updates, nil
-	}
-
-	updates, err := s.sendRequest(ctx, request)
-	if err != nil {
-		return err
-	}
-
-	if err := waitOnIMAPUpdates(ctx, updates); err != nil {
-		return fmt.Errorf("could not sync system labels: %w", err)
-	}
-
-	return nil
-}
-
 func (s *SyncUpdateApplier) SyncLabels(ctx context.Context, labels map[string]proton.Label) error {
 	request := func(ctx context.Context, _ usertypes.AddressMode, connectors map[string]*Connector) ([]imap.Update, error) {
-		return syncLabels(ctx, labels, maps.Values(connectors))
+		return syncLabels(ctx, labels, maps.Values(connectors), s.labelConflictManager)
 	}

 	updates, err := s.sendRequest(ctx, request)
@ -161,15 +130,34 @@ func (s *SyncUpdateApplier) SyncLabels(ctx context.Context, labels map[string]pr
 }

 // nolint:exhaustive
-func syncLabels(ctx context.Context, labels map[string]proton.Label, connectors []*Connector) ([]imap.Update, error) {
+func syncLabels(ctx context.Context, labels map[string]proton.Label, connectors []*Connector, labelConflictManager *LabelConflictManager) ([]imap.Update, error) {
 	var updates []imap.Update

+	userLabelConflictResolver := labelConflictManager.NewConflictResolver(connectors)
+	internalLabelConflictResolver := labelConflictManager.NewInternalLabelConflictResolver(connectors)
+
+	conflictUpdateGenerator, err := internalLabelConflictResolver.ResolveConflict(ctx, labels)
+	if err != nil {
+		return updates, err
+	}
+
+	for _, updateCh := range connectors {
+		conflictUpdates := conflictUpdateGenerator()
+		updateCh.publishUpdate(ctx, conflictUpdates...)
+		updates = append(updates, conflictUpdates...)
+	}
+
 	// Create placeholder Folders/Labels mailboxes with the \Noselect attribute.
 	for _, prefix := range []string{folderPrefix, labelPrefix} {
 		for _, updateCh := range connectors {
 			update := newPlaceHolderMailboxCreatedUpdate(prefix)
 			updateCh.publishUpdate(ctx, update)
 			updates = append(updates, update)
+
+			// Ensure we perform a rename operation as well. The created event won't update the name if the ID exists.
+			renameUpdate := imap.NewMailboxUpdated(imap.MailboxID(prefix), []string{prefix})
+			updateCh.publishUpdate(ctx, renameUpdate)
+			updates = append(updates, renameUpdate)
 		}
 	}

@ -188,7 +176,16 @@ func syncLabels(ctx context.Context, labels map[string]proton.Label, connectors
 			}

 		case proton.LabelTypeFolder, proton.LabelTypeLabel:
+			conflictUpdatesGenerator, err := userLabelConflictResolver.ResolveConflict(ctx, label, make(map[string]bool))
+			if err != nil {
+				return updates, err
+			}
+
 			for _, updateCh := range connectors {
+				conflictUpdates := conflictUpdatesGenerator()
+				updateCh.publishUpdate(ctx, conflictUpdates...)
+				updates = append(updates, conflictUpdates...)
+
 				update := newMailboxCreatedUpdate(imap.MailboxID(labelID), GetMailboxName(label))
 				updateCh.publishUpdate(ctx, update)
 				updates = append(updates, update)
--- a/internal/services/imapservice/utils.go
+++ b/internal/services/imapservice/utils.go
@ -0,0 +1,100 @@
+// Copyright (c) 2025 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package imapservice
+
+import (
+	"errors"
+
+	"github.com/ProtonMail/go-proton-api"
+	"github.com/ProtonMail/proton-bridge/v3/internal/usertypes"
+	"github.com/ProtonMail/proton-bridge/v3/pkg/message/parser"
+)
+
+type connectorInterface interface {
+	getSenderProtonAddress(p *parser.Parser) (proton.Address, error)
+	getAddress(id string) (proton.Address, bool)
+	getPrimaryAddress() (proton.Address, error)
+	getAddressMode() usertypes.AddressMode
+	logError(err error, errMsg string)
+}
+
+func (s *Connector) logError(err error, errMsg string) {
+	s.log.WithError(err).Warn(errMsg)
+}
+
+func (s *Connector) getAddressMode() usertypes.AddressMode {
+	return s.addressMode
+}
+
+func (s *Connector) getPrimaryAddress() (proton.Address, error) {
+	return s.identityState.GetPrimaryAddress()
+}
+
+func (s *Connector) getAddress(id string) (proton.Address, bool) {
+	return s.identityState.GetAddress(id)
+}
+
+func getImportAddress(p *parser.Parser, isDraft bool, id string, conn connectorInterface) (proton.Address, error) {
+	// addr is primary for combined mode or active for split mode
+	address, ok := conn.getAddress(id)
+	if !ok {
+		return proton.Address{}, errors.New("could not find account address")
+	}
+
+	// If the address is external and not BYOE - with sending enabled, then use the primary address as an import target.
+	if address.Type == proton.AddressTypeExternal && !address.Send {
+		var err error
+		address, err = conn.getPrimaryAddress()
+		if err != nil {
+			return proton.Address{}, errors.New("could not get primary account address")
+		}
+	}
+
+	inCombinedMode := conn.getAddressMode() == usertypes.AddressModeCombined
+	if !inCombinedMode {
+		return address, nil
+	}
+
+	senderAddr, err := conn.getSenderProtonAddress(p)
+	if err != nil {
+		if !errors.Is(err, errNoSenderAddressMatch) {
+			conn.logError(err, "Could not get import address")
+		}
+
+		// We did not find a match, so we use the default address.
+		return address, nil
+	}
+
+	if senderAddr.ID == address.ID {
+		return address, nil
+	}
+
+	// GODT-3185 / BRIDGE-120 In combined mode, in certain cases we adapt the address used for encryption.
+	// - draft with non-default address in combined mode: using sender address
+	// - import with non-default address in combined mode: using sender address
+	// - import with non-default disabled address in combined mode: using sender address
+	isSenderAddressDisabled := (!bool(senderAddr.Send)) || (senderAddr.Status != proton.AddressStatusEnabled)
+	isSenderExternalNonBYOE := senderAddr.Type == proton.AddressTypeExternal && !bool(senderAddr.Send)
+
+	// Forbid drafts/imports for external non-BYOE addresses
+	if isSenderExternalNonBYOE || (isDraft && isSenderAddressDisabled) {
+		return address, nil
+	}
+
+	return senderAddr, nil
+}
--- a/internal/services/imapservice/utils_test.go
+++ b/internal/services/imapservice/utils_test.go
@ -0,0 +1,380 @@
+// Copyright (c) 2025 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package imapservice
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/ProtonMail/go-proton-api"
+	"github.com/ProtonMail/proton-bridge/v3/internal/usertypes"
+	"github.com/ProtonMail/proton-bridge/v3/pkg/message/parser"
+	"github.com/stretchr/testify/require"
+)
+
+type testConnector struct {
+	addressMode        usertypes.AddressMode
+	primaryAddress     proton.Address
+	senderAddress      proton.Address
+	imapAddress        proton.Address
+	senderAddressError error
+}
+
+func (t *testConnector) getSenderProtonAddress(_ *parser.Parser) (proton.Address, error) {
+	return t.senderAddress, t.senderAddressError
+}
+
+func (t *testConnector) getAddress(_ string) (proton.Address, bool) {
+	return t.imapAddress, true
+}
+
+func (t *testConnector) getPrimaryAddress() (proton.Address, error) {
+	return t.primaryAddress, nil
+}
+
+func (t *testConnector) getAddressMode() usertypes.AddressMode {
+	return t.addressMode
+}
+
+func (t *testConnector) logError(_ error, _ string) {
+}
+
+func Test_GetImportAddress_SplitMode(t *testing.T) {
+	primaryAddress := proton.Address{
+		ID:      "1",
+		Email:   "primary@proton.me",
+		Send:    true,
+		Receive: true,
+		Type:    proton.AddressTypeOriginal,
+		Status:  proton.AddressStatusEnabled,
+	}
+
+	imapAddressProton := proton.Address{
+		ID:      "2",
+		Email:   "imap@proton.me",
+		Send:    true,
+		Receive: true,
+		Type:    proton.AddressTypeOriginal,
+	}
+
+	testConn := &testConnector{
+		addressMode:    usertypes.AddressModeSplit,
+		primaryAddress: primaryAddress,
+		imapAddress:    imapAddressProton,
+	}
+
+	// Import address is internal, we're creating a draft.
+	// Expected: returned address is internal.
+	addr, err := getImportAddress(nil, true, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, imapAddressProton.ID, addr.ID)
+	require.Equal(t, imapAddressProton.Email, addr.Email)
+
+	// Import address is internal, we're attempting to import a message.
+	// Expected: returned address is internal.
+	addr, err = getImportAddress(nil, false, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, imapAddressProton.ID, addr.ID)
+	require.Equal(t, imapAddressProton.Email, addr.Email)
+
+	imapAddressBYOE := proton.Address{
+		ID:      "3",
+		Email:   "byoe@external.com",
+		Send:    true,
+		Receive: true,
+		Type:    proton.AddressTypeExternal,
+	}
+
+	// IMAP address is BYOE, we're creating a draft
+	// Expected: returned address is BYOE.
+	testConn.imapAddress = imapAddressBYOE
+	addr, err = getImportAddress(nil, true, imapAddressBYOE.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, imapAddressBYOE.ID, addr.ID)
+	require.Equal(t, imapAddressBYOE.Email, addr.Email)
+	// IMAP address is BYOE, we're importing a message
+	// Expected: returned address is BYOE.
+	addr, err = getImportAddress(nil, false, imapAddressBYOE.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, imapAddressBYOE.ID, addr.ID)
+	require.Equal(t, imapAddressBYOE.Email, addr.Email)
+
+	imapAddressExternal := proton.Address{
+		ID:      "4",
+		Email:   "external@external.com",
+		Send:    false,
+		Receive: false,
+		Type:    proton.AddressTypeExternal,
+	}
+
+	// IMAP address is external, we're creating a draft.
+	// Expected: returned address is primary.
+	testConn.imapAddress = imapAddressExternal
+	addr, err = getImportAddress(nil, true, imapAddressExternal.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, primaryAddress.ID, addr.ID)
+	require.Equal(t, primaryAddress.Email, addr.Email)
+	// IMAP address is external, we're trying to import.
+	// Expected: returned address is primary.
+	addr, err = getImportAddress(nil, false, imapAddressExternal.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, primaryAddress.ID, addr.ID)
+	require.Equal(t, primaryAddress.Email, addr.Email)
+}
+
+func Test_GetImportAddress_CombinedMode_ProtonAddresses(t *testing.T) {
+	primaryAddress := proton.Address{
+		ID:      "1",
+		Email:   "primary@proton.me",
+		Send:    true,
+		Receive: true,
+		Type:    proton.AddressTypeOriginal,
+		Status:  proton.AddressStatusEnabled,
+	}
+
+	imapAddressProton := proton.Address{
+		ID:      "2",
+		Email:   "imap@proton.me",
+		Send:    true,
+		Receive: true,
+		Type:    proton.AddressTypeOriginal,
+	}
+
+	senderAddress := proton.Address{
+		ID:      "3",
+		Email:   "sender@proton.me",
+		Send:    true,
+		Receive: true,
+		Type:    proton.AddressTypeOriginal,
+		Status:  proton.AddressStatusEnabled,
+	}
+
+	testConn := &testConnector{
+		addressMode:    usertypes.AddressModeCombined,
+		primaryAddress: primaryAddress,
+		imapAddress:    imapAddressProton,
+		senderAddress:  senderAddress,
+	}
+
+	// Both the sender address and the imap address are the same. We're creating a draft.
+	// Expected: IMAP address is returned.
+	testConn.senderAddress = imapAddressProton
+	testConn.imapAddress = imapAddressProton
+	addr, err := getImportAddress(nil, true, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, imapAddressProton.ID, addr.ID)
+	require.Equal(t, imapAddressProton.Email, addr.Email)
+	// Both the sender address and the imap address are the same. We're trying to import
+	// Expected: IMAP address is returned.
+	addr, err = getImportAddress(nil, false, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, imapAddressProton.ID, addr.ID)
+	require.Equal(t, imapAddressProton.Email, addr.Email)
+
+	// Sender address and imap address are different. Sender address is enabled and has sending enabled.
+	// We're creating a draft.
+	// Expected: Sender address is returned.
+	testConn.senderAddress = senderAddress
+	testConn.imapAddress = imapAddressProton
+	addr, err = getImportAddress(nil, true, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, senderAddress.ID, addr.ID)
+	require.Equal(t, senderAddress.Email, addr.Email)
+	// Sender address and imap address are different. Sender address is enabled and has sending enabled.
+	// We're importing a message.
+	// Expected: Sender address is returned.
+	addr, err = getImportAddress(nil, false, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, senderAddress.ID, addr.ID)
+	require.Equal(t, senderAddress.Email, addr.Email)
+
+	// Sender address and imap address are different. Sender address is disabled, but has sending enabled.
+	// We're creating a draft message.
+	// Expected: IMAP address is returned.
+	senderAddress.Status = proton.AddressStatusDisabled
+	testConn.senderAddress = senderAddress
+	addr, err = getImportAddress(nil, true, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, imapAddressProton.ID, addr.ID)
+	require.Equal(t, imapAddressProton.Email, addr.Email)
+	// Sender address and imap address are different. Sender address is disabled, but has sending enabled.
+	// We're importing a message.
+	// Expected: IMAP address is returned.
+	addr, err = getImportAddress(nil, false, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, senderAddress.ID, addr.ID)
+	require.Equal(t, senderAddress.Email, addr.Email)
+
+	// Sender address and imap address are different. Sender address is enabled, but has sending disabled.
+	// We're creating a draft.
+	// Expected: IMAP address is returned.
+	senderAddress.Status = proton.AddressStatusEnabled
+	senderAddress.Send = false
+	testConn.senderAddress = senderAddress
+	addr, err = getImportAddress(nil, true, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, imapAddressProton.ID, addr.ID)
+	require.Equal(t, imapAddressProton.Email, addr.Email)
+	// Sender address and imap address are different. Sender address is enabled, but has sending disabled.
+	// We're importing a message.
+	// Expected: IMAP address is returned.
+	addr, err = getImportAddress(nil, false, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, senderAddress.ID, addr.ID)
+	require.Equal(t, senderAddress.Email, addr.Email)
+
+	// Sender address and imap address are different. But sender address is not an associated proton address.
+	// We're creating a draft.
+	// Expected: Sender address is returned.
+	testConn.senderAddressError = errors.New("sender address is not associated with the account")
+	addr, err = getImportAddress(nil, true, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, imapAddressProton.ID, addr.ID)
+	require.Equal(t, imapAddressProton.Email, addr.Email)
+	// Sender address and imap address are different. But sender address is not an associated proton address.
+	// We're importing a message.
+	// Expected: Sender address is returned.
+	addr, err = getImportAddress(nil, false, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, imapAddressProton.ID, addr.ID)
+	require.Equal(t, imapAddressProton.Email, addr.Email)
+}
+
+func Test_GetImportAddress_CombinedMode_ExternalAddresses(t *testing.T) {
+	primaryAddress := proton.Address{
+		ID:      "1",
+		Email:   "primary@proton.me",
+		Send:    true,
+		Receive: true,
+		Type:    proton.AddressTypeOriginal,
+		Status:  proton.AddressStatusEnabled,
+	}
+
+	imapAddressProton := proton.Address{
+		ID:      "2",
+		Email:   "imap@proton.me",
+		Send:    true,
+		Receive: true,
+		Type:    proton.AddressTypeOriginal,
+	}
+
+	senderAddressExternal := proton.Address{
+		ID:      "3",
+		Email:   "sender@external.me",
+		Send:    false,
+		Receive: false,
+		Type:    proton.AddressTypeExternal,
+		Status:  proton.AddressStatusEnabled,
+	}
+
+	senderAddressExternalSecondary := proton.Address{
+		ID:      "4",
+		Email:   "sender2@external.me",
+		Send:    false,
+		Receive: false,
+		Type:    proton.AddressTypeExternal,
+		Status:  proton.AddressStatusEnabled,
+	}
+
+	testConn := &testConnector{
+		addressMode:    usertypes.AddressModeCombined,
+		primaryAddress: primaryAddress,
+		imapAddress:    imapAddressProton,
+		senderAddress:  senderAddressExternal,
+	}
+
+	// Sender address is external, and we're creating a draft.
+	// Expected: IMAP address is returned.
+	testConn.senderAddress = senderAddressExternal
+	testConn.imapAddress = imapAddressProton
+	addr, err := getImportAddress(nil, true, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, imapAddressProton.ID, addr.ID)
+	require.Equal(t, imapAddressProton.Email, addr.Email)
+	// Sender address is external, and we're importing a message.
+	// Expected: IMAP address is returned.
+	addr, err = getImportAddress(nil, false, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, imapAddressProton.ID, addr.ID)
+	require.Equal(t, imapAddressProton.Email, addr.Email)
+
+	// Sender and IMAP address are external, and we're trying to import.
+	// Expected: Primary address is returned.
+	testConn.imapAddress = senderAddressExternalSecondary
+	addr, err = getImportAddress(nil, false, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, primaryAddress.ID, addr.ID)
+	require.Equal(t, primaryAddress.Email, addr.Email)
+	// Sender and IMAP address are external, and we're trying to create a draft.
+	// Expected: Primary address is returned.
+	addr, err = getImportAddress(nil, true, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, primaryAddress.ID, addr.ID)
+	require.Equal(t, primaryAddress.Email, addr.Email)
+}
+
+func Test_GetImportAddress_CombinedMode_BYOEAddresses(t *testing.T) {
+	primaryAddress := proton.Address{
+		ID:      "1",
+		Email:   "primary@proton.me",
+		Send:    true,
+		Receive: true,
+		Type:    proton.AddressTypeOriginal,
+		Status:  proton.AddressStatusEnabled,
+	}
+
+	imapAddressProton := proton.Address{
+		ID:      "2",
+		Email:   "imap@proton.me",
+		Send:    true,
+		Receive: true,
+		Type:    proton.AddressTypeOriginal,
+	}
+
+	senderAddressBYOE := proton.Address{
+		ID:      "3",
+		Email:   "sender@external.me",
+		Send:    true,
+		Receive: true,
+		Type:    proton.AddressTypeExternal,
+		Status:  proton.AddressStatusEnabled,
+	}
+
+	testConn := &testConnector{
+		addressMode:    usertypes.AddressModeCombined,
+		primaryAddress: primaryAddress,
+		imapAddress:    imapAddressProton,
+		senderAddress:  senderAddressBYOE,
+	}
+
+	// Sender address is BYOE, and we're creating a draft.
+	// Expected: BYOE address is returned.
+	testConn.senderAddress = senderAddressBYOE
+	testConn.imapAddress = imapAddressProton
+	addr, err := getImportAddress(nil, true, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, senderAddressBYOE.ID, addr.ID)
+	require.Equal(t, senderAddressBYOE.Email, addr.Email)
+
+	// Sender address is BYOE, and we're importing a message.
+	// Expected: BYOE address is returned.
+	addr, err = getImportAddress(nil, false, imapAddressProton.ID, testConn)
+	require.NoError(t, err)
+	require.Equal(t, senderAddressBYOE.ID, addr.ID)
+	require.Equal(t, senderAddressBYOE.Email, addr.Email)
+}
--- a/internal/services/imapsmtpserver/imap.go
+++ b/internal/services/imapsmtpserver/imap.go
@ -24,6 +24,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"time"

 	"github.com/Masterminds/semver/v3"
 	"github.com/ProtonMail/gluon"
@ -37,9 +38,16 @@ import (
 	"github.com/ProtonMail/proton-bridge/v3/internal/files"
 	"github.com/ProtonMail/proton-bridge/v3/internal/logging"
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/observability"
+	"github.com/ProtonMail/proton-bridge/v3/internal/unleash"
 	"github.com/sirupsen/logrus"
 )

+const (
+	rollingCounterNewConnectionThreshold = 300
+	rollingCounterNumberOfBuckets        = 6
+	rollingCounterBucketRotationInterval = time.Second * 10
+)
+
 var logIMAP = logrus.WithField("pkg", "server/imap") //nolint:gochecknoglobals

 type IMAPSettingsProvider interface {
@ -81,6 +89,7 @@ func newIMAPServer(
 	uidValidityGenerator imap.UIDValidityGenerator,
 	panicHandler async.PanicHandler,
 	observabilitySender observability.Sender,
+	featureFlagProvider unleash.FeatureFlagValueProvider,
 ) (*gluon.Server, error) {
 	gluonCacheDir = ApplyGluonCachePathSuffix(gluonCacheDir)
 	gluonConfigDir = ApplyGluonConfigPathSuffix(gluonConfigDir)
@ -126,6 +135,8 @@ func newIMAPServer(
 		gluon.WithUIDValidityGenerator(uidValidityGenerator),
 		gluon.WithPanicHandler(panicHandler),
 		gluon.WithObservabilitySender(observability.NewAdapter(observabilitySender), int(observability.GluonImapError), int(observability.GluonMessageError), int(observability.GluonOtherError)),
+		gluon.WithConnectionRollingCounter(rollingCounterNewConnectionThreshold, rollingCounterNumberOfBuckets, rollingCounterBucketRotationInterval),
+		gluon.WithFeatureFlagProvider(featureFlagProvider),
 	}

 	if disableIMAPAuthenticate {
--- a/internal/services/imapsmtpserver/service.go
+++ b/internal/services/imapsmtpserver/service.go
@ -34,6 +34,7 @@ import (
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/observability"
 	bridgesmtp "github.com/ProtonMail/proton-bridge/v3/internal/services/smtp"
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/syncservice"
+	"github.com/ProtonMail/proton-bridge/v3/internal/unleash"
 	"github.com/ProtonMail/proton-bridge/v3/pkg/cpc"
 	"github.com/emersion/go-smtp"
 	"github.com/sirupsen/logrus"
@ -63,6 +64,7 @@ type Service struct {
 	telemetry            Telemetry

 	observabilitySender observability.Sender
+	featureFlagProvider unleash.FeatureFlagValueProvider
 }

 func NewService(
@ -75,6 +77,7 @@ func NewService(
 	uidValidityGenerator imap.UIDValidityGenerator,
 	telemetry Telemetry,
 	observabilitySender observability.Sender,
+	featureFlagProvider unleash.FeatureFlagValueProvider,
 ) *Service {
 	return &Service{
 		requests:     cpc.NewCPC(),
@ -91,6 +94,7 @@ func NewService(
 		telemetry:            telemetry,

 		observabilitySender: observabilitySender,
+		featureFlagProvider: featureFlagProvider,
 	}
 }

@ -170,6 +174,14 @@ func (sm *Service) SetGluonDir(ctx context.Context, gluonDir string) error {
 	return err
 }

+func (sm *Service) LogRemoteLabelIDs(ctx context.Context, provider imapservice.GluonIDProvider, addrID ...string) error {
+	_, err := sm.requests.Send(ctx, &smRequestLogRemoteMailboxIDs{
+		addrID:     addrID,
+		idProvider: provider,
+	})
+	return err
+}
+
 func (sm *Service) RemoveIMAPUser(ctx context.Context, deleteData bool, provider imapservice.GluonIDProvider, addrID ...string) error {
 	_, err := sm.requests.Send(ctx, &smRequestRemoveIMAPUser{
 		withData:   deleteData,
@ -192,6 +204,22 @@ func (sm *Service) RemoveSMTPAccount(ctx context.Context, service *bridgesmtp.Se
 	return err
 }

+func (sm *Service) GetUserMailboxByName(ctx context.Context, addrID string, mailboxName []string) (imap.MailboxData, error) {
+	return sm.imapServer.GetUserMailboxByName(ctx, addrID, mailboxName)
+}
+
+func (sm *Service) GetUserMailboxCountByInternalID(ctx context.Context, addrID string, internalID imap.InternalMailboxID) (int, error) {
+	return sm.imapServer.GetUserMailboxCountByInternalID(ctx, addrID, internalID)
+}
+
+func (sm *Service) GetOpenIMAPSessionCount() int {
+	return sm.imapServer.GetOpenSessionCount()
+}
+
+func (sm *Service) GetRollingIMAPConnectionCount() int {
+	return sm.imapServer.GetRollingIMAPConnectionCount()
+}
+
 func (sm *Service) run(ctx context.Context, subscription events.Subscription) {
 	eventSub := subscription.Add()
 	defer subscription.Remove(eventSub)
@ -244,6 +272,10 @@ func (sm *Service) run(ctx context.Context, subscription events.Subscription) {
 					sm.handleLoadedUserCountChange(ctx)
 				}

+			case *smRequestLogRemoteMailboxIDs:
+				err := sm.logRemoteLabelIDsFromServer(ctx, r.addrID, r.idProvider)
+				request.Reply(ctx, nil, err)
+
 			case *smRequestRemoveIMAPUser:
 				err := sm.handleRemoveIMAPUser(ctx, r.withData, r.idProvider, r.addrID...)
 				request.Reply(ctx, nil, err)
@ -311,6 +343,35 @@ func (sm *Service) handleAddIMAPUser(ctx context.Context,
 	return sm.handleAddIMAPUserImpl(ctx, connector, addrID, idProvider, syncStateProvider)
 }

+func (sm *Service) logRemoteLabelIDsFromServer(ctx context.Context, addrIDs []string, idProvider imapservice.GluonIDProvider) error {
+	if sm.imapServer == nil {
+		return fmt.Errorf("no imap server instance running")
+	}
+
+	for _, addrID := range addrIDs {
+		gluonID, ok := idProvider.GetGluonID(addrID)
+		if !ok {
+			sm.log.Warnf("Could not find Gluon ID for addrID %v", addrID)
+			continue
+		}
+
+		log := sm.log.WithFields(logrus.Fields{
+			"addrID":  addrID,
+			"gluonID": gluonID,
+		})
+
+		remoteLabelIDs, err := sm.imapServer.GetAllMailboxRemoteIDsForUser(ctx, gluonID)
+		if err != nil {
+			log.WithError(err).Error("Could not obtain remote label IDs for user")
+			continue
+		}
+
+		log.WithField("remoteLabelIDs", remoteLabelIDs).Debug("Logging Gluon remote Label IDs")
+	}
+
+	return nil
+}
+
 func (sm *Service) handleAddIMAPUserImpl(ctx context.Context,
 	connector connector.Connector,
 	addrID string,
@ -457,6 +518,7 @@ func (sm *Service) createIMAPServer(ctx context.Context) (*gluon.Server, error)
 		sm.uidValidityGenerator,
 		sm.panicHandler,
 		sm.observabilitySender,
+		sm.featureFlagProvider,
 	)
 	if err == nil {
 		sm.eventPublisher.PublishEvent(ctx, events.IMAPServerCreated{})
@ -723,3 +785,8 @@ type smRequestAddSMTPAccount struct {
 type smRequestRemoveSMTPAccount struct {
 	account *bridgesmtp.Service
 }
+
+type smRequestLogRemoteMailboxIDs struct {
+	addrID     []string
+	idProvider imapservice.GluonIDProvider
+}
--- a/internal/services/notifications/service.go
+++ b/internal/services/notifications/service.go
@ -44,7 +44,7 @@ type Service struct {

 	store *Store

-	getFlagValueFn unleash.GetFlagValueFn
+	featureFlagValueProvider unleash.FeatureFlagValueProvider

 	observabilitySender observability.Sender
 }
@ -52,7 +52,7 @@ type Service struct {
 const bitfieldRegexPattern = `^\\\d+`

 func NewService(userID string, service userevents.Subscribable, eventPublisher events.EventPublisher, store *Store,
-	getFlagFn unleash.GetFlagValueFn, observabilitySender observability.Sender) *Service {
+	featureFlagValueProvider unleash.FeatureFlagValueProvider, observabilitySender observability.Sender) *Service {
 	return &Service{
 		userID: userID,

@ -68,8 +68,8 @@ func NewService(userID string, service userevents.Subscribable, eventPublisher e

 		store: store,

-		getFlagValueFn:      getFlagFn,
-		observabilitySender: observabilitySender,
+		featureFlagValueProvider: featureFlagValueProvider,
+		observabilitySender:      observabilitySender,
 	}
 }

@ -102,7 +102,7 @@ func (s *Service) run(ctx context.Context) {
 }

 func (s *Service) HandleNotificationEvents(ctx context.Context, notificationEvents []proton.NotificationEvent) error {
-	if s.getFlagValueFn(unleash.EventLoopNotificationDisabled) {
+	if s.featureFlagValueProvider.GetFlagValue(unleash.EventLoopNotificationDisabled) {
 		s.log.Info("Received notification events. Skipping as kill switch is enabled.")
 		return nil
 	}
--- a/internal/services/observability/adapter.go
+++ b/internal/services/observability/adapter.go
@ -19,6 +19,7 @@ package observability

 import (
 	"github.com/ProtonMail/go-proton-api"
+	"github.com/ProtonMail/proton-bridge/v3/internal/services/observability/gluonmetrics"
 )

 type Adapter struct {
@ -88,6 +89,15 @@ func (adapter *Adapter) AddDistinctMetrics(errType interface{}, metrics ...map[s
 	}

 	if len(typedMetrics) > 0 {
-		adapter.sender.AddDistinctMetrics(DistinctionErrorTypeEnum(errTypeInt), typedMetrics...)
+		adapter.sender.AddDistinctMetrics(DistinctionMetricTypeEnum(errTypeInt), typedMetrics...)
 	}
 }
+
+func (adapter *Adapter) AddIMAPConnectionsExceededThresholdMetric(totalOpenIMAPConnections, newIMAPConnections int) {
+	metric := gluonmetrics.GenerateNewOpenedIMAPConnectionsExceedThreshold(
+		adapter.sender.GetEmailClient(),
+		BucketIMAPConnections(totalOpenIMAPConnections),
+		BucketIMAPConnections(newIMAPConnections))
+
+	adapter.sender.AddTimeLimitedMetric(NewIMAPConnectionsExceedThreshold, metric)
+}
--- a/internal/services/observability/distinction_error_types.go
+++ b/internal/services/observability/distinction_error_types.go
@ -19,21 +19,22 @@ package observability

 import "time"

-// DistinctionErrorTypeEnum - maps to the specific error schema for which we
-// want to send a user update.
-type DistinctionErrorTypeEnum int
+// DistinctionMetricTypeEnum - used to distinct specific metrics which we want to limit over some interval.
+// Most enums are tied to a specific error schema for which we also send a specific distinction user update.
+type DistinctionMetricTypeEnum int

 const (
-	SyncError DistinctionErrorTypeEnum = iota
+	SyncError DistinctionMetricTypeEnum = iota
 	GluonImapError
 	GluonMessageError
 	GluonOtherError
 	SMTPError
 	EventLoopError // EventLoopError - should always be kept last when inserting new keys.
+	NewIMAPConnectionsExceedThreshold
 )

-// errorSchemaMap - maps between the DistinctionErrorTypeEnum and the relevant schema name.
-var errorSchemaMap = map[DistinctionErrorTypeEnum]string{ //nolint:gochecknoglobals
+// errorSchemaMap - maps between some DistinctionMetricTypeEnum and the relevant schema name.
+var errorSchemaMap = map[DistinctionMetricTypeEnum]string{ //nolint:gochecknoglobals
 	SyncError:         "bridge_sync_errors_users_total",
 	EventLoopError:    "bridge_event_loop_events_errors_users_total",
 	GluonImapError:    "bridge_gluon_imap_errors_users_total",
@ -43,9 +44,9 @@ var errorSchemaMap = map[DistinctionErrorTypeEnum]string{ //nolint:gochecknoglob
 }

 // createLastSentMap - needs to be updated whenever we make changes to the enum.
-func createLastSentMap() map[DistinctionErrorTypeEnum]time.Time {
+func createLastSentMap() map[DistinctionMetricTypeEnum]time.Time {
 	registerTime := time.Now().Add(-updateInterval)
-	lastSentMap := make(map[DistinctionErrorTypeEnum]time.Time)
+	lastSentMap := make(map[DistinctionMetricTypeEnum]time.Time)

 	for errType := SyncError; errType <= EventLoopError; errType++ {
 		lastSentMap[errType] = registerTime
--- a/internal/services/observability/distinction_utility.go
+++ b/internal/services/observability/distinction_utility.go
@ -40,7 +40,7 @@ type distinctionUtility struct {

 	panicHandler async.PanicHandler

-	lastSentMap map[DistinctionErrorTypeEnum]time.Time // Ensures we don't step over the limit of one user update every 5 mins.
+	lastSentMap map[DistinctionMetricTypeEnum]time.Time // Ensures we don't step over the limit of one user update every 5 mins.

 	observabilitySender observabilitySender
 	settingsGetter      settingsGetter
@ -87,7 +87,7 @@ func (d *distinctionUtility) setSettingsGetter(getter settingsGetter) {

 // checkAndUpdateLastSentMap - checks whether we have sent a relevant user update metric
 // within the last 5 minutes.
-func (d *distinctionUtility) checkAndUpdateLastSentMap(key DistinctionErrorTypeEnum) bool {
+func (d *distinctionUtility) checkAndUpdateLastSentMap(key DistinctionMetricTypeEnum) bool {
 	curTime := time.Now()
 	val, ok := d.lastSentMap[key]
 	if !ok {
@ -107,7 +107,7 @@ func (d *distinctionUtility) checkAndUpdateLastSentMap(key DistinctionErrorTypeE
 // and the relevant settings. In the future this will need to be expanded to support multiple
 // versions of the metric if we ever decide to change them.
 func (d *distinctionUtility) generateUserMetric(
-	metricType DistinctionErrorTypeEnum,
+	metricType DistinctionMetricTypeEnum,
 ) proton.ObservabilityMetric {
 	schemaName, ok := errorSchemaMap[metricType]
 	if !ok {
@ -138,7 +138,7 @@ func generateUserMetric(schemaName, plan, mailClient, dohEnabled, betaAccess str
 	}
 }

-func (d *distinctionUtility) generateDistinctMetrics(errType DistinctionErrorTypeEnum, metrics ...proton.ObservabilityMetric) []proton.ObservabilityMetric {
+func (d *distinctionUtility) generateDistinctMetrics(errType DistinctionMetricTypeEnum, metrics ...proton.ObservabilityMetric) []proton.ObservabilityMetric {
 	d.updateHeartbeatData(errType)

 	if d.checkAndUpdateLastSentMap(errType) {
--- a/internal/services/observability/gluonmetrics/metrics.go
+++ b/internal/services/observability/gluonmetrics/metrics.go
@ -0,0 +1,45 @@
+// Copyright (c) 2025 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package gluonmetrics
+
+import (
+	"time"
+
+	"github.com/ProtonMail/go-proton-api"
+)
+
+const (
+	newIMAPConnectionThresholdExceededSchemaName = "bridge_imap_recently_opened_connections_total"
+	newIMAPConnectionThresholdExceededVersion    = 1
+)
+
+func GenerateNewOpenedIMAPConnectionsExceedThreshold(emailClient, totalOpenIMAPConnectionCount, newlyOpenedIMAPConnectionCount string) proton.ObservabilityMetric {
+	return proton.ObservabilityMetric{
+		Name:      newIMAPConnectionThresholdExceededSchemaName,
+		Version:   newIMAPConnectionThresholdExceededVersion,
+		Timestamp: time.Now().Unix(),
+		Data: map[string]interface{}{
+			"Value": 1,
+			"Labels": map[string]string{
+				"mailClient":                                   emailClient,
+				"numberOfOpenIMAPConnectionsBuckets":           totalOpenIMAPConnectionCount,
+				"numberOfRecentlyOpenedIMAPConnectionsBuckets": newlyOpenedIMAPConnectionCount,
+			},
+		},
+	}
+}
--- a/internal/services/observability/heartbeat.go
+++ b/internal/services/observability/heartbeat.go
@ -42,7 +42,7 @@ func (d *distinctionUtility) resetHeartbeatData() {
 	d.heartbeatData.receivedGluonError = false
 }

-func (d *distinctionUtility) updateHeartbeatData(errType DistinctionErrorTypeEnum) {
+func (d *distinctionUtility) updateHeartbeatData(errType DistinctionMetricTypeEnum) {
 	d.withUpdateHeartbeatDataLock(func() {
 		//nolint:exhaustive
 		switch errType {
--- a/internal/services/observability/service.go
+++ b/internal/services/observability/service.go
@ -45,7 +45,9 @@ type client struct {
 // so we can easily pass them down to relevant components.
 type Sender interface {
 	AddMetrics(metrics ...proton.ObservabilityMetric)
-	AddDistinctMetrics(errType DistinctionErrorTypeEnum, metrics ...proton.ObservabilityMetric)
+	AddDistinctMetrics(errType DistinctionMetricTypeEnum, metrics ...proton.ObservabilityMetric)
+	AddTimeLimitedMetric(metricType DistinctionMetricTypeEnum, metric proton.ObservabilityMetric)
+	GetEmailClient() string
 }

 type Service struct {
@ -325,11 +327,25 @@ func (s *Service) AddMetrics(metrics ...proton.ObservabilityMetric) {
 // what number of events come from what number of users.
 // As the binning interval is what allows us to do this we
 // should not send these if there are no logged-in users at that moment.
-func (s *Service) AddDistinctMetrics(errType DistinctionErrorTypeEnum, metrics ...proton.ObservabilityMetric) {
+func (s *Service) AddDistinctMetrics(errType DistinctionMetricTypeEnum, metrics ...proton.ObservabilityMetric) {
 	metrics = s.distinctionUtility.generateDistinctMetrics(errType, metrics...)
 	s.addMetricsIfClients(metrics...)
 }

+// AddTimeLimitedMetric - schedules a metric to be sent if a metric of the same type has not been sent within some interval.
+// The interval is defined in the distinction utility.
+func (s *Service) AddTimeLimitedMetric(metricType DistinctionMetricTypeEnum, metric proton.ObservabilityMetric) {
+	if !s.distinctionUtility.checkAndUpdateLastSentMap(metricType) {
+		return
+	}
+
+	s.addMetricsIfClients(metric)
+}
+
+func (s *Service) GetEmailClient() string {
+	return s.distinctionUtility.getEmailClientUserAgent()
+}
+
 // ModifyHeartbeatInterval - should only be used for testing. Resets the heartbeat ticker.
 func (s *Service) ModifyHeartbeatInterval(duration time.Duration) {
 	s.distinctionUtility.heartbeatTicker.Reset(duration)
--- a/internal/services/observability/utils.go
+++ b/internal/services/observability/utils.go
@ -66,3 +66,30 @@ func getEnabled(value bool) string {
 	}
 	return "enabled"
 }
+
+func BucketIMAPConnections(val int) string {
+	switch {
+	case val < 10:
+		return "<10"
+	case val < 25:
+		return "10-24"
+	case val < 50:
+		return "25-49"
+	case val < 100:
+		return "50-99"
+	case val < 200:
+		return "100-199"
+	case val < 300:
+		return "200-299"
+	case val < 500:
+		return "300-499"
+	case val < 1000:
+		return "500-999"
+	case val < 2000:
+		return "1000-1999"
+	case val < 3000:
+		return "2000-2999"
+	default:
+		return "3000+"
+	}
+}
--- a/internal/services/smtp/observabilitymetrics/metrics.go
+++ b/internal/services/smtp/observabilitymetrics/metrics.go
@ -21,6 +21,7 @@ import (
 	"time"

 	"github.com/ProtonMail/go-proton-api"
+	"github.com/ProtonMail/proton-bridge/v3/internal/services/observability"
 )

 const (
@ -29,6 +30,9 @@ const (

 	smtpSendSuccessSchemaName    = "bridge_smtp_send_success_total"
 	smtpSendSuccessSchemaVersion = 1
+
+	smtpSubmissionRequestSchemaName    = "bridge_smtp_send_request_total"
+	smtpSubmissionRequestSchemaVersion = 1
 )

 func generateSMTPErrorObservabilityMetric(errorType string) proton.ObservabilityMetric {
@ -88,3 +92,19 @@ func GenerateSMTPSendSuccess() proton.ObservabilityMetric {
 		},
 	}
 }
+
+func GenerateSMTPSubmissionRequest(emailClient string, numberOfOpenIMAPConnections, numberOfRecentlyOpenedIMAPConnections int) proton.ObservabilityMetric {
+	return proton.ObservabilityMetric{
+		Name:      smtpSubmissionRequestSchemaName,
+		Version:   smtpSubmissionRequestSchemaVersion,
+		Timestamp: time.Now().Unix(),
+		Data: map[string]interface{}{
+			"Value": 1,
+			"Labels": map[string]string{
+				"numberOfOpenIMAPConnections":           observability.BucketIMAPConnections(numberOfOpenIMAPConnections),
+				"numberOfRecentlyOpenedIMAPConnections": observability.BucketIMAPConnections(numberOfRecentlyOpenedIMAPConnections),
+				"mailClient":                            emailClient,
+			},
+		},
+	}
+}
--- a/internal/services/smtp/service.go
+++ b/internal/services/smtp/service.go
@ -32,13 +32,24 @@ import (
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/observability"
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/orderedtasks"
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/sendrecorder"
+	"github.com/ProtonMail/proton-bridge/v3/internal/services/smtp/observabilitymetrics"
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/userevents"
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/useridentity"
+	"github.com/ProtonMail/proton-bridge/v3/internal/unleash"
 	"github.com/ProtonMail/proton-bridge/v3/internal/usertypes"
 	"github.com/ProtonMail/proton-bridge/v3/pkg/cpc"
 	"github.com/sirupsen/logrus"
 )

+const (
+	newlyOpenedIMAPConnectionsThreshold = 300
+)
+
+type imapSessionCountProvider interface {
+	GetOpenIMAPSessionCount() int
+	GetRollingIMAPConnectionCount() int
+}
+
 type Service struct {
 	userID       string
 	panicHandler async.PanicHandler
@ -59,6 +70,9 @@ type Service struct {
 	serverManager ServerManager

 	observabilitySender observability.Sender
+
+	imapSessionCountProvider imapSessionCountProvider
+	featureFlagValueProvider unleash.FeatureFlagValueProvider
 }

 func NewService(
@ -74,6 +88,8 @@ func NewService(
 	identityState *useridentity.State,
 	serverManager ServerManager,
 	observabilitySender observability.Sender,
+	imapSessionCountProvider imapSessionCountProvider,
+	featureFlagValueProvider unleash.FeatureFlagValueProvider,
 ) *Service {
 	subscriberName := fmt.Sprintf("smpt-%v", userID)

@ -99,7 +115,9 @@ func NewService(
 		addressMode:   mode,
 		serverManager: serverManager,

-		observabilitySender: observabilitySender,
+		imapSessionCountProvider: imapSessionCountProvider,
+		observabilitySender:      observabilitySender,
+		featureFlagValueProvider: featureFlagValueProvider,
 	}
 }

@ -207,7 +225,6 @@ func (s *Service) run(ctx context.Context) {

 			switch r := request.Value().(type) {
 			case *sendMailReq:
-				s.log.Debug("Received send mail request")
 				err := s.sendMail(ctx, r)
 				request.Reply(ctx, nil, err)

@ -252,16 +269,38 @@ type sendMailReq struct {

 func (s *Service) sendMail(ctx context.Context, req *sendMailReq) error {
 	defer async.HandlePanic(s.panicHandler)
+
+	openSessionCount := s.imapSessionCountProvider.GetOpenIMAPSessionCount()
+	newlyOpenedSessions := s.imapSessionCountProvider.GetRollingIMAPConnectionCount()
+	log := s.log.WithFields(logrus.Fields{
+		"newlyOpenedIMAPConnectionsCount": newlyOpenedSessions,
+		"openIMAPConnectionsCount":        openSessionCount,
+	})
+	log.Debug("Received send mail request")
+
+	// Send SMTP send request metric to observability.
+	s.observabilitySender.AddMetrics(observabilitymetrics.GenerateSMTPSubmissionRequest(s.observabilitySender.GetEmailClient(), openSessionCount, newlyOpenedSessions))
+
+	// Send report to sentry if kill switch is disabled & number of newly opened IMAP connections exceed threshold.
+	if !s.featureFlagValueProvider.GetFlagValue(unleash.SMTPSubmissionRequestSentryReportDisabled) && newlyOpenedSessions >= newlyOpenedIMAPConnectionsThreshold {
+		if err := s.reporter.ReportMessageWithContext("SMTP Send Mail Request - newly opened IMAP connections exceed threshold", reporter.Context{
+			"newlyOpenedIMAPConnectionsCount": newlyOpenedSessions,
+			"openIMAPConnectionsCount":        openSessionCount,
+			"emailClient":                     s.observabilitySender.GetEmailClient(),
+		}); err != nil {
+			s.log.WithError(err).Error("Failed to submit report to sentry (SMTP Send Mail Request)")
+		}
+	}
+
 	start := time.Now()
-	s.log.Debug("Received send mail request")
 	defer func() {
 		end := time.Now()
-		s.log.Debugf("Send mail request finished in %v", end.Sub(start))
+		log.Debugf("Send mail request finished in %v", end.Sub(start))
 	}()

 	if err := s.smtpSendMail(ctx, req.authID, req.from, req.to, req.r); err != nil {
 		if apiErr := new(proton.APIError); errors.As(err, &apiErr) {
-			s.log.WithError(apiErr).WithField("Details", apiErr.DetailsToString()).Error("failed to send message")
+			log.WithError(apiErr).WithField("Details", apiErr.DetailsToString()).Error("failed to send message")
 		}

 		return err
--- a/internal/services/syncservice/handler.go
+++ b/internal/services/syncservice/handler.go
@ -19,10 +19,13 @@ package syncservice

 import (
 	"context"
+	"errors"
 	"fmt"
 	"time"

 	"github.com/ProtonMail/gluon/async"
+	"github.com/ProtonMail/gluon/db"
+	"github.com/ProtonMail/gluon/reporter"
 	"github.com/ProtonMail/go-proton-api"
 	"github.com/ProtonMail/proton-bridge/v3/internal/network"
 	"github.com/sirupsen/logrus"
@ -33,6 +36,10 @@ const NumSyncStages = 4

 type LabelMap = map[string]proton.Label

+type labelConflictChecker interface {
+	CheckAndReportConflicts(ctx context.Context, labels map[string]proton.Label) error
+}
+
 // Handler is the interface from which we control the syncing of the IMAP data. One instance should be created for each
 // user and used for every subsequent sync request.
 type Handler struct {
@ -45,6 +52,7 @@ type Handler struct {
 	syncFinishedCh chan error
 	panicHandler   async.PanicHandler
 	downloadCache  *DownloadCache
+	sentryReporter reporter.Reporter
 }

 func NewHandler(
@ -54,6 +62,7 @@ func NewHandler(
 	state StateProvider,
 	log *logrus.Entry,
 	panicHandler async.PanicHandler,
+	sentryReporter reporter.Reporter,
 ) *Handler {
 	return &Handler{
 		client:         client,
@ -65,6 +74,7 @@ func NewHandler(
 		regulator:      regulator,
 		panicHandler:   panicHandler,
 		downloadCache:  newDownloadCache(),
+		sentryReporter: sentryReporter,
 	}
 }

@ -91,12 +101,17 @@ func (t *Handler) Execute(
 	updateApplier UpdateApplier,
 	messageBuilder MessageBuilder,
 	coolDown time.Duration,
+	labelConflictChecker labelConflictChecker,
 ) {
 	t.log.Info("Sync triggered")
 	t.group.Once(func(ctx context.Context) {
 		start := time.Now()
 		t.log.WithField("start", start).Info("Beginning user sync")

+		if err := labelConflictChecker.CheckAndReportConflicts(ctx, labels); err != nil {
+			t.log.WithError(err).Error("Failed to check and report label conflicts")
+		}
+
 		syncReporter.OnStart(ctx)
 		var err error
 		for {
@ -104,6 +119,20 @@ func (t *Handler) Execute(
 				t.log.WithError(err).Error("Sync aborted")
 				break
 			} else if err = t.run(ctx, syncReporter, labels, updateApplier, messageBuilder); err != nil {
+				if db.IsUniqueLabelConstraintError(err) {
+					if sentryErr := t.sentryReporter.ReportMessageWithContext("Failed to sync due to label unique constraint conflict",
+						reporter.Context{"err": err}); sentryErr != nil {
+						t.log.WithError(sentryErr).Error("Failed to report label unique constraint conflict error to Sentry")
+					}
+				} else if !(errors.Is(err, context.Canceled)) {
+					if sentryErr := t.sentryReporter.ReportMessageWithContext("Failed to sync, will retry later", reporter.Context{
+						"err":     err.Error(),
+						"user_id": t.userID,
+					}); sentryErr != nil {
+						t.log.WithError(sentryErr).Error("Failed to report sentry message")
+					}
+				}
+
 				t.log.WithError(err).Error("Failed to sync, will retry later")
 				sleepCtx(ctx, coolDown)
 			} else {
@ -138,11 +167,10 @@ func (t *Handler) run(ctx context.Context,
 	}

 	if syncStatus.IsComplete() {
-		t.log.Info("Sync already complete, only system labels will be updated")
-
-		if err := updateApplier.SyncSystemLabelsOnly(ctx, labels); err != nil {
-			t.log.WithError(err).Error("Failed to sync system labels")
+		t.log.Info("Sync already complete, updating labels")

+		if err := updateApplier.SyncLabels(ctx, labels); err != nil {
+			t.log.WithError(err).Error("Failed to sync labels")
 			return err
 		}

--- a/internal/services/syncservice/handler_test.go
+++ b/internal/services/syncservice/handler_test.go
@ -25,6 +25,7 @@ import (

 	"github.com/ProtonMail/gluon/async"
 	"github.com/ProtonMail/go-proton-api"
+	"github.com/ProtonMail/proton-bridge/v3/internal/sentry"
 	"github.com/bradenaw/juniper/xmaps"
 	"github.com/golang/mock/gomock"
 	"github.com/sirupsen/logrus"
@ -74,8 +75,7 @@ func TestTask_NoStateAndSucceeds(t *testing.T) {
 	}

 	{
-		call1 := tt.updateApplier.EXPECT().SyncLabels(gomock.Any(), gomock.Eq(labels)).Times(1).Return(nil)
-		tt.updateApplier.EXPECT().SyncSystemLabelsOnly(gomock.Any(), gomock.Eq(labels)).After(call1).Times(1).Return(nil)
+		tt.updateApplier.EXPECT().SyncLabels(gomock.Any(), gomock.Eq(labels)).Times(2).Return(nil)
 	}

 	{
@ -203,12 +203,19 @@ func TestTask_StateHasSyncedState(t *testing.T) {
 		}, nil
 	})

-	tt.updateApplier.EXPECT().SyncSystemLabelsOnly(gomock.Any(), gomock.Eq(labels)).Return(nil)
+	tt.updateApplier.EXPECT().SyncLabels(gomock.Any(), gomock.Eq(labels)).Return(nil)

 	err := tt.task.run(context.Background(), tt.syncReporter, labels, tt.updateApplier, tt.messageBuilder)
 	require.NoError(t, err)
 }

+type mockLabelConflictChecker struct {
+}
+
+func (m *mockLabelConflictChecker) CheckAndReportConflicts(_ context.Context, _ map[string]proton.Label) error {
+	return nil
+}
+
 func TestTask_RepeatsOnSyncFailure(t *testing.T) {
 	const MessageTotal int64 = 50
 	const MessageID string = "foo"
@ -272,7 +279,7 @@ func TestTask_RepeatsOnSyncFailure(t *testing.T) {
 	tt.syncReporter.EXPECT().OnFinished(gomock.Any())
 	tt.syncReporter.EXPECT().OnProgress(gomock.Any(), gomock.Eq(MessageDelta))

-	tt.task.Execute(tt.syncReporter, labels, tt.updateApplier, tt.messageBuilder, time.Microsecond)
+	tt.task.Execute(tt.syncReporter, labels, tt.updateApplier, tt.messageBuilder, time.Microsecond, &mockLabelConflictChecker{})
 	require.NoError(t, <-tt.task.OnSyncFinishedCH())
 }

@ -343,7 +350,7 @@ func newTestHandler(mockCtrl *gomock.Controller, userID string) thandler { // no
 	client := NewMockAPIClient(mockCtrl)
 	messageBuilder := NewMockMessageBuilder(mockCtrl)
 	syncReporter := NewMockReporter(mockCtrl)
-	task := NewHandler(regulator, client, userID, syncState, logrus.WithField("test", "test"), &async.NoopPanicHandler{})
+	task := NewHandler(regulator, client, userID, syncState, logrus.WithField("test", "test"), &async.NoopPanicHandler{}, sentry.NullSentryReporter{})

 	return thandler{
 		task:           task,
--- a/internal/services/syncservice/interfaces.go
+++ b/internal/services/syncservice/interfaces.go
@ -80,7 +80,6 @@ type MessageBuilder interface {

 type UpdateApplier interface {
 	ApplySyncUpdates(ctx context.Context, updates []BuildResult) error
-	SyncSystemLabelsOnly(ctx context.Context, labels map[string]proton.Label) error
 	SyncLabels(ctx context.Context, labels map[string]proton.Label) error
 }

--- a/internal/services/syncservice/mocks_test.go
+++ b/internal/services/syncservice/mocks_test.go
@ -548,20 +548,6 @@ func (mr *MockUpdateApplierMockRecorder) SyncLabels(arg0, arg1 interface{}) *gom
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "SyncLabels", reflect.TypeOf((*MockUpdateApplier)(nil).SyncLabels), arg0, arg1)
 }

-// SyncSystemLabelsOnly mocks base method.
-func (m *MockUpdateApplier) SyncSystemLabelsOnly(arg0 context.Context, arg1 map[string]proton.Label) error {
-	m.ctrl.T.Helper()
-	ret := m.ctrl.Call(m, "SyncSystemLabelsOnly", arg0, arg1)
-	ret0, _ := ret[0].(error)
-	return ret0
-}
-
-// SyncSystemLabelsOnly indicates an expected call of SyncSystemLabelsOnly.
-func (mr *MockUpdateApplierMockRecorder) SyncSystemLabelsOnly(arg0, arg1 interface{}) *gomock.Call {
-	mr.mock.ctrl.T.Helper()
-	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "SyncSystemLabelsOnly", reflect.TypeOf((*MockUpdateApplier)(nil).SyncSystemLabelsOnly), arg0, arg1)
-}
-
 // MockMessageBuilder is a mock of MessageBuilder interface.
 type MockMessageBuilder struct {
 	ctrl     *gomock.Controller
--- a/internal/services/userevents/service.go
+++ b/internal/services/userevents/service.go
@ -29,6 +29,8 @@ import (
 	"time"

 	"github.com/ProtonMail/gluon/async"
+	"github.com/ProtonMail/gluon/db"
+	"github.com/ProtonMail/gluon/reporter"
 	"github.com/ProtonMail/gluon/watcher"
 	"github.com/ProtonMail/go-proton-api"
 	"github.com/ProtonMail/proton-bridge/v3/internal"
@ -70,6 +72,8 @@ type Service struct {
 	eventPollWaitersLock sync.Mutex
 	eventSubscription    events.Subscription
 	eventWatcher         *watcher.Watcher[events.Event]
+
+	sentryReporter reporter.Reporter
 }

 func NewService(
@ -82,6 +86,7 @@ func NewService(
 	eventTimeout time.Duration,
 	panicHandler async.PanicHandler,
 	eventSubscription events.Subscription,
+	sentryReporter reporter.Reporter,
 ) *Service {
 	return &Service{
 		cpc:          cpc.NewCPC(),
@ -99,6 +104,7 @@ func NewService(
 		panicHandler:      panicHandler,
 		eventSubscription: eventSubscription,
 		eventWatcher:      eventSubscription.Add(events.ConnStatusDown{}, events.ConnStatusUp{}),
+		sentryReporter:    sentryReporter,
 	}
 }

@ -414,6 +420,14 @@ func (s *Service) handleEventError(ctx context.Context, lastEventID string, even
 		return subscriberName, fmt.Errorf("failed to handle event due to server error: %w", err)
 	}

+	if db.IsUniqueLabelConstraintError(err) {
+		if err := s.sentryReporter.ReportMessageWithContext("Unique label constraint error occurred on event", reporter.Context{
+			"err": err,
+		}); err != nil {
+			s.log.WithError(err).Error("Failed to report label constraint error to sentry")
+		}
+	}
+
 	// Otherwise, the error is a client-side issue; notify bridge to handle it.
 	s.log.WithField("event", event).Warn("Failed to handle API event")

--- a/internal/services/userevents/service_handle_event_error_test.go
+++ b/internal/services/userevents/service_handle_event_error_test.go
@ -30,6 +30,7 @@ import (
 	"github.com/ProtonMail/go-proton-api"
 	"github.com/ProtonMail/proton-bridge/v3/internal/events"
 	"github.com/ProtonMail/proton-bridge/v3/internal/events/mocks"
+	"github.com/ProtonMail/proton-bridge/v3/internal/sentry"
 	"github.com/golang/mock/gomock"
 	"github.com/stretchr/testify/require"
 )
@ -49,6 +50,7 @@ func TestServiceHandleEventError_SubscriberEventUnwrapping(t *testing.T) {
 		time.Second,
 		async.NoopPanicHandler{},
 		events.NewNullSubscription(),
+		sentry.NullSentryReporter{},
 	)

 	lastEventID := "PrevEvent"
@ -87,6 +89,7 @@ func TestServiceHandleEventError_BadEventPutsServiceOnPause(t *testing.T) {
 		time.Second,
 		async.NoopPanicHandler{},
 		events.NewNullSubscription(),
+		sentry.NullSentryReporter{},
 	)
 	service.Resume()
 	lastEventID := "PrevEvent"
@ -121,6 +124,7 @@ func TestServiceHandleEventError_BadEventFromPublishTimeout(t *testing.T) {
 		time.Second,
 		async.NoopPanicHandler{},
 		events.NewNullSubscription(),
+		sentry.NullSentryReporter{},
 	)
 	lastEventID := "PrevEvent"
 	event := proton.Event{EventID: "MyEvent"}
@ -152,6 +156,7 @@ func TestServiceHandleEventError_NoBadEventCheck(t *testing.T) {
 		time.Second,
 		async.NoopPanicHandler{},
 		events.NewNullSubscription(),
+		sentry.NullSentryReporter{},
 	)
 	lastEventID := "PrevEvent"
 	event := proton.Event{EventID: "MyEvent"}
@ -178,6 +183,7 @@ func TestServiceHandleEventError_JsonUnmarshalEventProducesUncategorizedErrorEve
 		time.Second,
 		async.NoopPanicHandler{},
 		events.NewNullSubscription(),
+		sentry.NullSentryReporter{},
 	)
 	lastEventID := "PrevEvent"
 	event := proton.Event{EventID: "MyEvent"}
--- a/internal/services/userevents/service_handle_event_test.go
+++ b/internal/services/userevents/service_handle_event_test.go
@ -28,6 +28,7 @@ import (
 	"github.com/ProtonMail/go-proton-api"
 	"github.com/ProtonMail/proton-bridge/v3/internal/events"
 	"github.com/ProtonMail/proton-bridge/v3/internal/events/mocks"
+	"github.com/ProtonMail/proton-bridge/v3/internal/sentry"
 	"github.com/golang/mock/gomock"
 	"github.com/stretchr/testify/require"
 )
@ -69,6 +70,7 @@ func TestServiceHandleEvent_CheckEventCategoriesHandledInOrder(t *testing.T) {
 		10*time.Second,
 		async.NoopPanicHandler{},
 		events.NewNullSubscription(),
+		sentry.NullSentryReporter{},
 	)

 	subscription := NewCallbackSubscriber("test", EventHandler{
@ -130,6 +132,7 @@ func TestServiceHandleEvent_CheckEventFailureCausesError(t *testing.T) {
 		time.Second,
 		async.NoopPanicHandler{},
 		events.NewNullSubscription(),
+		sentry.NullSentryReporter{},
 	)

 	subscription := NewCallbackSubscriber("test", EventHandler{
@ -168,6 +171,7 @@ func TestServiceHandleEvent_CheckEventFailureCausesErrorParallel(t *testing.T) {
 		time.Second,
 		async.NoopPanicHandler{},
 		events.NewNullSubscription(),
+		sentry.NullSentryReporter{},
 	)

 	subscription := NewCallbackSubscriber("test", EventHandler{
--- a/internal/services/userevents/service_test.go
+++ b/internal/services/userevents/service_test.go
@ -27,6 +27,7 @@ import (
 	"github.com/ProtonMail/go-proton-api"
 	"github.com/ProtonMail/proton-bridge/v3/internal/events"
 	mocks2 "github.com/ProtonMail/proton-bridge/v3/internal/events/mocks"
+	"github.com/ProtonMail/proton-bridge/v3/internal/sentry"
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/orderedtasks"
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/userevents/mocks"
 	"github.com/golang/mock/gomock"
@ -76,6 +77,7 @@ func TestService_EventIDLoadStore(t *testing.T) {
 		time.Second,
 		async.NoopPanicHandler{},
 		events.NewNullSubscription(),
+		sentry.NullSentryReporter{},
 	)

 	_, err := service.Start(context.Background(), group)
@ -132,6 +134,7 @@ func TestService_RetryEventOnNonCatastrophicFailure(t *testing.T) {
 		time.Second,
 		async.NoopPanicHandler{},
 		events.NewNullSubscription(),
+		sentry.NullSentryReporter{},
 	)
 	service.Subscribe(NewCallbackSubscriber("foo", EventHandler{MessageHandler: subscriber}))

@ -182,6 +185,7 @@ func TestService_OnBadEventServiceIsPaused(t *testing.T) {
 		time.Second,
 		async.NoopPanicHandler{},
 		events.NewNullSubscription(),
+		sentry.NullSentryReporter{},
 	)

 	// Event publisher expectations.
@ -249,6 +253,7 @@ func TestService_UnsubscribeDuringEventHandlingDoesNotCauseDeadlock(t *testing.T
 		time.Second,
 		async.NoopPanicHandler{},
 		events.NewNullSubscription(),
+		sentry.NullSentryReporter{},
 	)

 	subscription := NewCallbackSubscriber("foo", EventHandler{MessageHandler: subscriber})
@ -309,6 +314,7 @@ func TestService_UnsubscribeBeforeHandlingEventIsNotConsideredError(t *testing.T
 		time.Second,
 		async.NoopPanicHandler{},
 		events.NewNullSubscription(),
+		sentry.NullSentryReporter{},
 	)

 	subscription := NewEventSubscriber("Foo")
@ -369,6 +375,7 @@ func TestService_WaitOnEventPublishAfterPause(t *testing.T) {
 		time.Second,
 		async.NoopPanicHandler{},
 		events.NewNullSubscription(),
+		sentry.NullSentryReporter{},
 	)

 	subscriber.EXPECT().HandleMessageEvents(gomock.Any(), gomock.Eq(messageEvents)).Times(1).DoAndReturn(func(_ context.Context, _ []proton.MessageEvent) error {
@ -442,6 +449,7 @@ func TestService_EventRewind(t *testing.T) {
 		time.Second,
 		async.NoopPanicHandler{},
 		events.NewNullSubscription(),
+		sentry.NullSentryReporter{},
 	)

 	_, err := service.Start(context.Background(), group)
--- a/internal/unleash/service.go
+++ b/internal/unleash/service.go
@ -37,14 +37,32 @@ var pollJitter = 2 * time.Minute  //nolint:gochecknoglobals
 const filename = "unleash_flags"

 const (
-	EventLoopNotificationDisabled       = "InboxBridgeEventLoopNotificationDisabled"
-	IMAPAuthenticateCommandDisabled     = "InboxBridgeImapAuthenticateCommandDisabled"
-	UserRemovalGluonDataCleanupDisabled = "InboxBridgeUserRemovalGluonDataCleanupDisabled"
+	EventLoopNotificationDisabled                 = "InboxBridgeEventLoopNotificationDisabled"
+	IMAPAuthenticateCommandDisabled               = "InboxBridgeImapAuthenticateCommandDisabled"
+	UserRemovalGluonDataCleanupDisabled           = "InboxBridgeUserRemovalGluonDataCleanupDisabled"
+	UpdateUseNewVersionFileStructureDisabled      = "InboxBridgeUpdateWithOsFilterDisabled"
+	LabelConflictResolverDisabled                 = "InboxBridgeLabelConflictResolverDisabled"
+	SMTPSubmissionRequestSentryReportDisabled     = "InboxBridgeSmtpSubmissionRequestSentryReportDisabled"
+	InternalLabelConflictResolverDisabled         = "InboxBridgeUnexpectedFoldersLabelsStartupFixupDisabled"
+	ItnternalLabelConflictNonEmptyMailboxDeletion = "InboxBridgeUnknownNonEmptyMailboxDeletion"
 )

-type requestFeaturesFn func(ctx context.Context) (proton.FeatureFlagResult, error)
-type GetFlagValueFn func(key string) bool
+type FeatureFlagValueProvider interface {
+	GetFlagValue(key string) bool
+}

+// NullUnleashService - mock of the unleash service. Should be used for testing.
+type NullUnleashService struct{}
+
+func (n NullUnleashService) GetFlagValue(_ string) bool {
+	return false
+}
+
+func NewNullUnleashService() *NullUnleashService {
+	return &NullUnleashService{}
+}
+
+type requestFeaturesFn func(ctx context.Context) (proton.FeatureFlagResult, error)
 type Service struct {
 	panicHandler async.PanicHandler
 	timer        *proton.Ticker
--- a/internal/updater/types_test.go
+++ b/internal/updater/types_test.go
@ -0,0 +1,255 @@
+// Copyright (c) 2025 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
+
+package updater
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func Test_ReleaseCategory_UpdateEligible(t *testing.T) {
+	// If release is beta only beta users can update
+	require.True(t, EarlyAccessReleaseCategory.UpdateEligible(EarlyChannel))
+	require.False(t, EarlyAccessReleaseCategory.UpdateEligible(StableChannel))
+
+	// If the release is stable and is the newest then both beta and stable users can update
+	require.True(t, StableReleaseCategory.UpdateEligible(EarlyChannel))
+	require.True(t, StableReleaseCategory.UpdateEligible(StableChannel))
+}
+
+func Test_ReleaseCategory_JsonUnmarshal(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected ReleaseCategory
+		wantErr  bool
+	}{
+		{
+			input:    `{"ReleaseCategory": "EarlyAccess"}`,
+			expected: EarlyAccessReleaseCategory,
+		},
+		{
+			input:    `{"ReleaseCategory": "Earlyaccess"}`,
+			expected: EarlyAccessReleaseCategory,
+		},
+		{
+			input:    `{"ReleaseCategory": "earlyaccess"}`,
+			expected: EarlyAccessReleaseCategory,
+		},
+		{
+			input:    `{"ReleaseCategory": "   earlyaccess   "}`,
+			expected: EarlyAccessReleaseCategory,
+		},
+		{
+			input:    `{"ReleaseCategory": "Stable"}`,
+			expected: StableReleaseCategory,
+		},
+		{
+			input:    `{"ReleaseCategory": "Stable   "}`,
+			expected: StableReleaseCategory,
+		},
+		{
+			input:    `{"ReleaseCategory": "stable"}`,
+			expected: StableReleaseCategory,
+		},
+		{
+			input:   `{"ReleaseCategory": "invalid"}`,
+			wantErr: true,
+		},
+	}
+
+	var data struct {
+		ReleaseCategory ReleaseCategory
+	}
+
+	for _, test := range tests {
+		err := json.Unmarshal([]byte(test.input), &data)
+		if err != nil && !test.wantErr {
+			t.Errorf("json.Unmarshal() error = %v, wantErr %v", err, test.wantErr)
+			return
+		}
+
+		if test.wantErr && err == nil {
+			t.Errorf("expected err got nil")
+		}
+
+		if !test.wantErr && data.ReleaseCategory != test.expected {
+			t.Errorf("got %v, want %v", data.ReleaseCategory, test.expected)
+		}
+	}
+}
+
+func Test_ReleaseCategory_JsonMarshal(t *testing.T) {
+	tests := []struct {
+		input struct {
+			ReleaseCategory ReleaseCategory `json:"ReleaseCategory"`
+		}
+		expectedOutput string
+		wantErr        bool
+	}{
+		{
+			input: struct {
+				ReleaseCategory ReleaseCategory `json:"ReleaseCategory"`
+			}{ReleaseCategory: StableReleaseCategory},
+			expectedOutput: `{"ReleaseCategory":"Stable"}`,
+		},
+		{
+			input: struct {
+				ReleaseCategory ReleaseCategory `json:"ReleaseCategory"`
+			}{ReleaseCategory: EarlyAccessReleaseCategory},
+			expectedOutput: `{"ReleaseCategory":"EarlyAccess"}`,
+		},
+		{
+			input: struct {
+				ReleaseCategory ReleaseCategory `json:"ReleaseCategory"`
+			}{ReleaseCategory: 4},
+			wantErr: true,
+		},
+	}
+
+	for _, test := range tests {
+		output, err := json.Marshal(test.input)
+
+		if test.wantErr {
+			if err == nil && len(output) == 0 {
+				t.Errorf("expected error or non-empty output for invalid category")
+				return
+			}
+		} else {
+			if err != nil {
+				t.Errorf("unexpected error: %v", err)
+				return
+			}
+
+			if string(output) != test.expectedOutput {
+				t.Errorf("json.Marshal() = %v, want %v", string(output), test.expectedOutput)
+			}
+		}
+	}
+}
+
+func Test_FileIdentifier_JsonUnmarshal(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected FileIdentifier
+		wantErr  bool
+	}{
+		{
+			input:    `{"Identifier": "package"}`,
+			expected: PackageIdentifier,
+		},
+		{
+			input:    `{"Identifier": "Package"}`,
+			expected: PackageIdentifier,
+		},
+		{
+			input:    `{"Identifier": "pACKage"}`,
+			expected: PackageIdentifier,
+		},
+		{
+			input:    `{"Identifier": "pACKage    "}`,
+			expected: PackageIdentifier,
+		},
+		{
+			input:    `{"Identifier": "installer"}`,
+			expected: InstallerIdentifier,
+		},
+		{
+			input:    `{"Identifier": "Installer"}`,
+			expected: InstallerIdentifier,
+		},
+		{
+			input:    `{"Identifier": "iNSTaller  "}`,
+			expected: InstallerIdentifier,
+		},
+		{
+			input:   `{"Identifier": "error"}`,
+			wantErr: true,
+		},
+	}
+
+	var data struct {
+		Identifier FileIdentifier
+	}
+
+	for _, test := range tests {
+		err := json.Unmarshal([]byte(test.input), &data)
+		if err != nil && !test.wantErr {
+			t.Errorf("json.Unmarshal() error = %v, wantErr %v", err, test.wantErr)
+			return
+		}
+
+		if test.wantErr && err == nil {
+			t.Errorf("expected err got nil")
+		}
+
+		if !test.wantErr && data.Identifier != test.expected {
+			t.Errorf("got %v, want %v", data.Identifier, test.expected)
+		}
+	}
+}
+
+func Test_FileIdentifier_JsonMarshal(t *testing.T) {
+	tests := []struct {
+		input struct {
+			Identifier FileIdentifier
+		}
+		expectedOutput string
+		wantErr        bool
+	}{
+		{
+			input: struct {
+				Identifier FileIdentifier
+			}{Identifier: PackageIdentifier},
+			expectedOutput: `{"Identifier":"package"}`,
+		},
+		{
+			input: struct {
+				Identifier FileIdentifier
+			}{Identifier: InstallerIdentifier},
+			expectedOutput: `{"Identifier":"installer"}`,
+		},
+		{
+			input: struct {
+				Identifier FileIdentifier
+			}{Identifier: 4},
+			wantErr: true,
+		},
+	}
+
+	for _, test := range tests {
+		output, err := json.Marshal(test.input)
+
+		if test.wantErr {
+			if err == nil && len(output) == 0 {
+				t.Errorf("expected error or non-empty output for invalid identifier")
+				return
+			}
+		} else {
+			if err != nil {
+				t.Errorf("unexpected error: %v", err)
+				return
+			}
+
+			if string(output) != test.expectedOutput {
+				t.Errorf("json.Marshal() = %v, want %v", string(output), test.expectedOutput)
+			}
+		}
+	}
+}
--- a/internal/updater/types_version.go
+++ b/internal/updater/types_version.go
@ -0,0 +1,135 @@
+// Copyright (c) 2025 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
+
+package updater
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+)
+
+type ReleaseCategory uint8
+type FileIdentifier uint8
+
+const (
+	EarlyAccessReleaseCategory ReleaseCategory = iota
+	StableReleaseCategory
+)
+
+const (
+	PackageIdentifier FileIdentifier = iota
+	InstallerIdentifier
+)
+
+var (
+	releaseCategoryName = map[uint8]string{ //nolint:gochecknoglobals
+		0: "EarlyAccess",
+		1: "Stable",
+	}
+	releaseCategoryValue = map[string]uint8{ //nolint:gochecknoglobals
+		"earlyaccess": 0,
+		"stable":      1,
+	}
+	fileIdentifierName = map[uint8]string{ //nolint:gochecknoglobals
+		0: "package",
+		1: "installer",
+	}
+	fileIdentifierValue = map[string]uint8{ //nolint:gochecknoglobals
+		"package":   0,
+		"installer": 1,
+	}
+)
+
+func ParseFileIdentifier(s string) (FileIdentifier, error) {
+	s = strings.TrimSpace(strings.ToLower(s))
+	val, ok := fileIdentifierValue[s]
+	if !ok {
+		return FileIdentifier(0), fmt.Errorf("%s is not a valid file identifier", s)
+	}
+
+	return FileIdentifier(val), nil
+}
+
+func (fi FileIdentifier) String() string {
+	return fileIdentifierName[uint8(fi)]
+}
+
+func (fi FileIdentifier) MarshalJSON() ([]byte, error) {
+	return json.Marshal(fi.String())
+}
+
+func (fi *FileIdentifier) UnmarshalJSON(data []byte) (err error) {
+	var fileIdentifier string
+	if err := json.Unmarshal(data, &fileIdentifier); err != nil {
+		return err
+	}
+
+	parsedFileIdentifier, err := ParseFileIdentifier(fileIdentifier)
+	if err != nil {
+		return err
+	}
+
+	*fi = parsedFileIdentifier
+	return nil
+}
+
+func ParseReleaseCategory(s string) (ReleaseCategory, error) {
+	s = strings.TrimSpace(strings.ToLower(s))
+	val, ok := releaseCategoryValue[s]
+	if !ok {
+		return ReleaseCategory(0), fmt.Errorf("%s is not a valid release category", s)
+	}
+
+	return ReleaseCategory(val), nil
+}
+
+func (rc ReleaseCategory) String() string {
+	return releaseCategoryName[uint8(rc)]
+}
+
+func (rc ReleaseCategory) MarshalJSON() ([]byte, error) {
+	return json.Marshal(rc.String())
+}
+
+func (rc *ReleaseCategory) UnmarshalJSON(data []byte) (err error) {
+	var releaseCat string
+	if err := json.Unmarshal(data, &releaseCat); err != nil {
+		return err
+	}
+
+	parsedCat, err := ParseReleaseCategory(releaseCat)
+	if err != nil {
+		return err
+	}
+
+	*rc = parsedCat
+
+	return nil
+}
+
+func (rc ReleaseCategory) UpdateEligible(channel Channel) bool {
+	if channel == StableChannel && rc == StableReleaseCategory {
+		return true
+	}
+
+	if channel == EarlyChannel && rc == EarlyAccessReleaseCategory || rc == StableReleaseCategory {
+		return true
+	}
+
+	return false
+}
--- a/internal/updater/updater.go
+++ b/internal/updater/updater.go
@ -29,13 +29,17 @@ import (
 	"github.com/ProtonMail/proton-bridge/v3/internal/versioner"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
+	"golang.org/x/exp/slices"
 )

+const updateFileVersion = 1
+
 var (
 	ErrDownloadVerify              = errors.New("failed to download or verify the update")
 	ErrInstall                     = errors.New("failed to install the update")
 	ErrUpdateAlreadyInstalled      = errors.New("update is already installed")
 	ErrVersionFileDownloadOrVerify = errors.New("failed to download or verify the version file")
+	ErrReleaseUpdatePackageMissing = errors.New("release update package is missing")
 )

 type Downloader interface {
@ -53,6 +57,7 @@ type Updater struct {
 	verifier  *crypto.KeyRing
 	product   string
 	platform  string
+	version   uint
 }

 func NewUpdater(ver *versioner.Versioner, verifier *crypto.KeyRing, product, platform string) *Updater {
@ -62,10 +67,36 @@ func NewUpdater(ver *versioner.Versioner, verifier *crypto.KeyRing, product, pla
 		verifier:  verifier,
 		product:   product,
 		platform:  platform,
+		version:   updateFileVersion,
 	}
 }

-func (u *Updater) GetVersionInfo(ctx context.Context, downloader Downloader, channel Channel) (VersionInfo, error) {
+func (u *Updater) GetVersionInfoLegacy(ctx context.Context, downloader Downloader, channel Channel) (VersionInfoLegacy, error) {
+	b, err := downloader.DownloadAndVerify(
+		ctx,
+		u.verifier,
+		u.getVersionFileURLLegacy(),
+		u.getVersionFileURLLegacy()+".sig",
+	)
+	if err != nil {
+		return VersionInfoLegacy{}, fmt.Errorf("%w: %w", ErrVersionFileDownloadOrVerify, err)
+	}
+
+	var versionMap VersionMap
+
+	if err := json.Unmarshal(b, &versionMap); err != nil {
+		return VersionInfoLegacy{}, err
+	}
+
+	version, ok := versionMap[channel]
+	if !ok {
+		return VersionInfoLegacy{}, errors.New("no updates available for this channel")
+	}
+
+	return version, nil
+}
+
+func (u *Updater) GetVersionInfo(ctx context.Context, downloader Downloader) (VersionInfo, error) {
 	b, err := downloader.DownloadAndVerify(
 		ctx,
 		u.verifier,
@ -76,21 +107,16 @@ func (u *Updater) GetVersionInfo(ctx context.Context, downloader Downloader, cha
 		return VersionInfo{}, fmt.Errorf("%w: %w", ErrVersionFileDownloadOrVerify, err)
 	}

-	var versionMap VersionMap
+	var releases VersionInfo

-	if err := json.Unmarshal(b, &versionMap); err != nil {
+	if err := json.Unmarshal(b, &releases); err != nil {
 		return VersionInfo{}, err
 	}

-	version, ok := versionMap[channel]
-	if !ok {
-		return VersionInfo{}, errors.New("no updates available for this channel")
-	}
-
-	return version, nil
+	return releases, nil
 }

-func (u *Updater) InstallUpdate(ctx context.Context, downloader Downloader, update VersionInfo) error {
+func (u *Updater) InstallUpdateLegacy(ctx context.Context, downloader Downloader, update VersionInfoLegacy) error {
 	if u.installer.IsAlreadyInstalled(update.Version) {
 		return ErrUpdateAlreadyInstalled
 	}
@ -113,13 +139,64 @@ func (u *Updater) InstallUpdate(ctx context.Context, downloader Downloader, upda
 	return nil
 }

+func (u *Updater) InstallUpdate(ctx context.Context, downloader Downloader, release Release) error {
+	if u.installer.IsAlreadyInstalled(release.Version) {
+		return ErrUpdateAlreadyInstalled
+	}
+
+	// Find update package
+	idx := slices.IndexFunc(release.File, func(file File) bool {
+		return file.Identifier == PackageIdentifier
+	})
+
+	if idx == -1 {
+		logrus.WithFields(logrus.Fields{
+			"release_version": release.Version,
+		}).Error("Update release does not contain update package")
+		return ErrReleaseUpdatePackageMissing
+	}
+
+	releaseUpdatePackage := release.File[idx]
+
+	b, err := downloader.DownloadAndVerify(
+		ctx,
+		u.verifier,
+		releaseUpdatePackage.URL,
+		releaseUpdatePackage.URL+".sig",
+	)
+	if err != nil {
+		return fmt.Errorf("%w: %w", ErrDownloadVerify, err)
+	}
+
+	if err := u.installer.InstallUpdate(release.Version, bytes.NewReader(b)); err != nil {
+		logrus.WithError(err).Error("Failed to install update")
+		return ErrInstall
+	}
+
+	return nil
+}
+
 func (u *Updater) RemoveOldUpdates() error {
 	return u.versioner.RemoveOldVersions()
 }

-// getVersionFileURL returns the URL of the version file.
+// getVersionFileURLLegacy returns the URL of the version file.
 // For example:
 //   - https://protonmail.com/download/bridge/version_linux.json
-func (u *Updater) getVersionFileURL() string {
+func (u *Updater) getVersionFileURLLegacy() string {
 	return fmt.Sprintf("%v/%v/version_%v.json", Host, u.product, u.platform)
 }
+
+// getVersionFileURL returns the URL of the version file.
+// For example:
+//   - https://protonmail.com/download/windows/x86/v1/version.json
+//   - https://protonmail.com/download/linux/x86/v1/version.json
+//   - https://protonmail.com/download/darwin/universal/v1/version.json
+func (u *Updater) getVersionFileURL() string {
+	switch u.platform {
+	case "darwin":
+		return fmt.Sprintf("%v/%v/%v/universal/v%v/version.json", Host, u.product, u.platform, u.version)
+	default:
+		return fmt.Sprintf("%v/%v/%v/x86/v%v/version.json", Host, u.product, u.platform, u.version)
+	}
+}
--- a/internal/updater/version.go
+++ b/internal/updater/version.go
@ -19,10 +19,36 @@ package updater

 import (
 	"github.com/Masterminds/semver/v3"
+	"github.com/ProtonMail/proton-bridge/v3/internal/updater/versioncompare"
 )

-// VersionInfo is information about one version of the app.
+type File struct {
+	URL            string         `json:"Url"`
+	Sha512CheckSum string         `json:"Sha512CheckSum,omitempty"`
+	Identifier     FileIdentifier `json:"Identifier"`
+}
+
+type Release struct {
+	ReleaseCategory   ReleaseCategory `json:"CategoryName"`
+	Version           *semver.Version
+	SystemVersion     versioncompare.SystemVersion `json:"SystemVersion,omitempty"`
+	RolloutProportion float64
+	MinAuto           *semver.Version `json:"MinAuto,omitempty"`
+	ReleaseNotesPage  string
+	LandingPage       string
+	File              []File `json:"File"`
+}
+
+func (rel Release) IsEmpty() bool {
+	return rel.Version == nil && len(rel.File) == 0
+}
+
 type VersionInfo struct {
+	Releases []Release `json:"Releases"`
+}
+
+// VersionInfoLegacy is information about one version of the app.
+type VersionInfoLegacy struct {
 	// Version is the semantic version of the release.
 	Version *semver.Version

@ -46,6 +72,10 @@ type VersionInfo struct {
 	RolloutProportion float64
 }

+func (verInfo VersionInfoLegacy) IsEmpty() bool {
+	return verInfo.Version == nil && verInfo.ReleaseNotesPage == ""
+}
+
 // VersionMap represents the structure of the version.json file.
 // It looks like this:
 //
@ -79,4 +109,4 @@ type VersionInfo struct {
 //	  }
 //	}.

-type VersionMap map[Channel]VersionInfo
+type VersionMap map[Channel]VersionInfoLegacy
--- a/internal/updater/version_test.go
+++ b/internal/updater/version_test.go
@ -0,0 +1,205 @@
+// Copyright (c) 2025 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
+
+package updater
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/Masterminds/semver/v3"
+	"github.com/ProtonMail/proton-bridge/v3/internal/updater/versioncompare"
+)
+
+var mockJSONData = `
+{
+  "Releases": [
+    {
+      "CategoryName": "Stable",
+      "Version": "2.1.0",
+      "ReleaseDate": "2025-01-15T08:00:00Z",
+      "File": [
+        {
+          "Url": "https://downloads.example.com/v2.1.0/MyApp-2.1.0.pkg",
+          "Sha512CheckSum": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
+          "Identifier": "package"
+        },
+        {
+          "Url": "https://downloads.example.com/v2.1.0/MyApp-2.1.0.dmg",
+          "Sha512CheckSum": "cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce",
+          "Identifier": "installer"
+        }
+      ],
+      "RolloutProportion": 0.5,
+      "MinAuto": "2.0.0",
+      "Commit": "8f52d45c9f8c31aa391315ea24e40c4a7e0b2c1d",
+      "ReleaseNotesPage": "https://example.com/releases/2.1.0/notes",
+      "LandingPage": "https://example.com/releases/2.1.0"
+    },
+    {
+      "CategoryName": "EarlyAccess",
+      "Version": "2.2.0-beta.1",
+      "ReleaseDate": "2025-01-20T10:00:00Z",
+      "File": [
+        {
+          "Url": "https://downloads.example.com/beta/v2.2.0-beta.1/MyApp-2.2.0-beta.1.pkg",
+          "Sha512CheckSum": "a9f0e44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
+          "Identifier": "package"
+        }
+      ],
+      "SystemVersion": {
+        "Minimum": "13"
+      },
+      "RolloutProportion": 0.25,
+      "MinAuto": "2.1.0",
+      "Commit": "3e72d45c9f8c31aa391315ea24e40c4a7e0b2c1d",
+      "ReleaseNotesPage": "https://example.com/releases/2.2.0-beta.1/notes",
+      "LandingPage": "https://example.com/releases/2.2.0-beta.1"
+    },
+    {
+      "CategoryName": "Stable",
+      "Version": "2.0.0",
+      "ReleaseDate": "2024-12-01T09:00:00Z",
+      "File": [
+        {
+          "Url": "https://downloads.example.com/v2.0.0/MyApp-2.0.0.pkg",
+          "Sha512CheckSum": "b5f0e44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
+          "Identifier": "package"
+        },
+        {
+          "Url": "https://downloads.example.com/v2.0.0/MyApp-2.0.0.dmg",
+          "Sha512CheckSum": "d583e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce",
+          "Identifier": "installer"
+        }
+      ],
+      "SystemVersion": {
+			"Maximum": "12.0.0",
+			"Minimum": "1.0.0"
+		},
+      "RolloutProportion": 1.0,
+      "MinAuto": "1.9.0",
+      "Commit": "2a42d45c9f8c31aa391315ea24e40c4a7e0b2c1d",
+      "ReleaseNotesPage": "https://example.com/releases/2.0.0/notes",
+      "LandingPage": "https://example.com/releases/2.0.0"
+    }
+  ]
+}
+`
+
+var expectedVersionInfo = VersionInfo{
+	Releases: []Release{
+		{
+			ReleaseCategory:   StableReleaseCategory,
+			Version:           semver.MustParse("2.1.0"),
+			RolloutProportion: 0.5,
+			MinAuto:           semver.MustParse("2.0.0"),
+			File: []File{
+				{
+					URL:        "https://downloads.example.com/v2.1.0/MyApp-2.1.0.pkg",
+					Identifier: PackageIdentifier,
+				},
+				{
+					URL:        "https://downloads.example.com/v2.1.0/MyApp-2.1.0.dmg",
+					Identifier: InstallerIdentifier,
+				},
+			},
+		},
+		{
+			ReleaseCategory:   EarlyAccessReleaseCategory,
+			Version:           semver.MustParse("2.2.0-beta.1"),
+			RolloutProportion: 0.25,
+			MinAuto:           semver.MustParse("2.1.0"),
+			File: []File{
+				{
+					URL:        "https://downloads.example.com/beta/v2.2.0-beta.1/MyApp-2.2.0-beta.1.pkg",
+					Identifier: PackageIdentifier,
+				},
+			},
+			SystemVersion: versioncompare.SystemVersion{Minimum: "13"},
+		},
+		{
+			ReleaseCategory:   StableReleaseCategory,
+			Version:           semver.MustParse("2.0.0"),
+			RolloutProportion: 1.0,
+			MinAuto:           semver.MustParse("1.9.0"),
+			SystemVersion:     versioncompare.SystemVersion{Maximum: "12.0.0", Minimum: "1.0.0"},
+			File: []File{
+				{
+					URL:        "https://downloads.example.com/v2.0.0/MyApp-2.0.0.pkg",
+					Identifier: PackageIdentifier,
+				},
+				{
+					URL:        "https://downloads.example.com/v2.0.0/MyApp-2.0.0.dmg",
+					Identifier: InstallerIdentifier,
+				},
+			},
+		},
+	},
+}
+
+func Test_Releases_JsonParse(t *testing.T) {
+	var versionInfo VersionInfo
+	if err := json.Unmarshal([]byte(mockJSONData), &versionInfo); err != nil {
+		t.Fatalf("Failed to parse JSON: %v", err)
+	}
+
+	if len(expectedVersionInfo.Releases) != len(versionInfo.Releases) {
+		t.Fatalf("expected %d releases, parsed %d releases", len(expectedVersionInfo.Releases), len(versionInfo.Releases))
+	}
+
+	for i, expectedRelease := range expectedVersionInfo.Releases {
+		release := versionInfo.Releases[i]
+
+		if release.ReleaseCategory != expectedRelease.ReleaseCategory {
+			t.Errorf("Release %d: expected category %v, got %v", i, expectedRelease.ReleaseCategory, release.ReleaseCategory)
+		}
+
+		if release.Version.String() != expectedRelease.Version.String() {
+			t.Errorf("Release %d: expected version %s, got %s", i, expectedRelease.Version, release.Version)
+		}
+
+		if release.RolloutProportion != expectedRelease.RolloutProportion {
+			t.Errorf("Release %d: expected rollout proportion %f, got %f", i, expectedRelease.RolloutProportion, release.RolloutProportion)
+		}
+
+		if expectedRelease.MinAuto != nil && release.MinAuto.String() != expectedRelease.MinAuto.String() {
+			t.Errorf("Release %d: expected min auto %s, got %s", i, expectedRelease.MinAuto, release.MinAuto)
+		}
+
+		if expectedRelease.SystemVersion.Minimum != release.SystemVersion.Minimum {
+			t.Errorf("Release %d: expected system version minimum %s, got %s", i, expectedRelease.SystemVersion.Minimum, release.SystemVersion.Minimum)
+		}
+
+		if expectedRelease.SystemVersion.Maximum != release.SystemVersion.Maximum {
+			t.Errorf("Release %d: expected system version minimum %s, got %s", i, expectedRelease.SystemVersion.Maximum, release.SystemVersion.Maximum)
+		}
+
+		if len(release.File) != len(expectedRelease.File) {
+			t.Errorf("Release %d: expected %d files, got %d", i, len(expectedRelease.File), len(release.File))
+		}
+
+		for j, expectedFile := range expectedRelease.File {
+			file := release.File[j]
+			if file.URL != expectedFile.URL {
+				t.Errorf("Release %d, File %d: expected URL %s, got %s", i, j, expectedFile.URL, file.URL)
+			}
+			if file.Identifier != expectedFile.Identifier {
+				t.Errorf("Release %d, File %d: expected Identifier %v, got %v", i, j, expectedFile.Identifier, file.Identifier)
+			}
+		}
+	}
+}
--- a/internal/updater/versioncompare/compare_darwin.go
+++ b/internal/updater/versioncompare/compare_darwin.go
@ -0,0 +1,134 @@
+// Copyright (c) 2025 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
+
+//go:build darwin
+
+package versioncompare
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/elastic/go-sysinfo/types"
+	"github.com/sirupsen/logrus"
+)
+
+func (sysVer SystemVersion) IsHostVersionEligible(log *logrus.Entry, host types.Host, getHostOSVersion func(host types.Host) string) (bool, error) {
+	if sysVer.Minimum == "" && sysVer.Maximum == "" {
+		return true, nil
+	}
+
+	// We use getHostOSVersion simply for testing; It's passed via Bridge.
+	var hostVersion string
+	if getHostOSVersion == nil {
+		hostVersion = host.Info().OS.Version
+	} else {
+		hostVersion = getHostOSVersion(host)
+	}
+
+	log.Debugf("Checking host OS and update system version requirements. Host: %s; Maximum: %s; Minimum: %s",
+		hostVersion, sysVer.Maximum, sysVer.Minimum)
+
+	hostVersionArr := strings.Split(hostVersion, ".")
+	if len(hostVersionArr) == 0 || hostVersion == "" {
+		return true, fmt.Errorf("could not get host version: %v", hostVersion)
+	}
+
+	hostVersionArrInt := make([]int, len(hostVersionArr))
+	for i := 0; i < len(hostVersionArr); i++ {
+		hostNum, err := strconv.Atoi(hostVersionArr[i])
+		if err != nil {
+			// If we receive an alphanumeric version - we should continue with the update and stop checking for
+			// OS version requirements.
+			return true, fmt.Errorf("invalid host version number: %s - %s", hostVersionArr[i], hostVersion)
+		}
+		hostVersionArrInt[i] = hostNum
+	}
+
+	if sysVer.Minimum != "" {
+		pass, err := compareMinimumVersion(hostVersionArrInt, sysVer.Minimum)
+		if err != nil {
+			return false, err
+		}
+
+		if !pass {
+			return false, fmt.Errorf("host version is below minimum: hostVersion %v - minimumVersion %v", hostVersion, sysVer.Minimum)
+		}
+	}
+
+	if sysVer.Maximum != "" {
+		pass, err := compareMaximumVersion(hostVersionArrInt, sysVer.Maximum)
+		if err != nil {
+			return false, err
+		}
+
+		if !pass {
+			return false, fmt.Errorf("host version is above maximum version: hostVersion %v - minimumVersion %v", hostVersion, sysVer.Maximum)
+		}
+	}
+
+	return true, nil
+}
+
+func compareMinimumVersion(hostVersionArr []int, minVersion string) (bool, error) {
+	minVersionArr := strings.Split(minVersion, ".")
+	iterationDepth := min(len(hostVersionArr), len(minVersionArr))
+
+	for i := 0; i < iterationDepth; i++ {
+		hostNum := hostVersionArr[i]
+
+		minNum, err := strconv.Atoi(minVersionArr[i])
+		if err != nil {
+			return false, fmt.Errorf("invalid minimum version number: %s - %s", minVersionArr[i], minVersion)
+		}
+
+		if hostNum < minNum {
+			return false, nil
+		}
+
+		if hostNum > minNum {
+			return true, nil
+		}
+	}
+
+	return true, nil // minVersion is inclusive
+}
+
+func compareMaximumVersion(hostVersionArr []int, maxVersion string) (bool, error) {
+	maxVersionArr := strings.Split(maxVersion, ".")
+	iterationDepth := min(len(maxVersionArr), len(hostVersionArr))
+
+	for i := 0; i < iterationDepth; i++ {
+		hostNum := hostVersionArr[i]
+
+		maxNum, err := strconv.Atoi(maxVersionArr[i])
+		if err != nil {
+			return false, fmt.Errorf("invalid maximum version number: %s - %s", maxVersionArr[i], maxVersion)
+		}
+
+		if hostNum > maxNum {
+			return false, nil
+		}
+
+		if hostNum < maxNum {
+			return true, nil
+		}
+	}
+
+	return true, nil // maxVersion is inclusive
+}
--- a/internal/updater/versioncompare/compare_darwin_test.go
+++ b/internal/updater/versioncompare/compare_darwin_test.go
@ -0,0 +1,105 @@
+// Copyright (c) 2025 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
+
+//go:build darwin
+
+package versioncompare
+
+import (
+	"testing"
+
+	"github.com/elastic/go-sysinfo"
+	"github.com/elastic/go-sysinfo/types"
+	"github.com/sirupsen/logrus"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_IsHost_EligibleDarwin(t *testing.T) {
+	host, err := sysinfo.Host()
+	require.NoError(t, err)
+
+	testData := []struct {
+		sysVer             SystemVersion
+		getHostOsVersionFn func(host types.Host) string
+		shouldContinue     bool
+		wantErr            bool
+	}{
+		{
+			sysVer:             SystemVersion{Minimum: "9.5", Maximum: "12.0"},
+			getHostOsVersionFn: func(_ types.Host) string { return "10.0" },
+			shouldContinue:     true,
+		},
+		{
+			sysVer:             SystemVersion{Minimum: "9.5.5.5", Maximum: "10.1.1.0"},
+			getHostOsVersionFn: func(_ types.Host) string { return "10.0" },
+			shouldContinue:     true,
+		},
+		{
+			sysVer:             SystemVersion{Minimum: "10.0.1", Maximum: "12.0"},
+			getHostOsVersionFn: func(_ types.Host) string { return "10.0" },
+			shouldContinue:     true,
+		},
+		{
+			sysVer:             SystemVersion{Minimum: "11.0", Maximum: "12.0"},
+			getHostOsVersionFn: func(_ types.Host) string { return "10.0" },
+			shouldContinue:     false,
+			wantErr:            true,
+		},
+		{
+			sysVer:             SystemVersion{Minimum: "11.1.0", Maximum: "12.0.0"},
+			getHostOsVersionFn: func(_ types.Host) string { return "11.0.0" },
+			shouldContinue:     false,
+			wantErr:            true,
+		},
+		{
+			sysVer:             SystemVersion{Minimum: "10.0", Maximum: "12.0"},
+			getHostOsVersionFn: func(_ types.Host) string { return "12.0" },
+			shouldContinue:     true,
+		},
+		{
+			sysVer:             SystemVersion{Minimum: "11.1.0", Maximum: "12.0.0"},
+			getHostOsVersionFn: func(_ types.Host) string { return "" },
+			shouldContinue:     true,
+			wantErr:            true,
+		},
+		{
+			sysVer:             SystemVersion{Minimum: "11.1.0", Maximum: "12.0.0"},
+			getHostOsVersionFn: func(_ types.Host) string { return "a.b.c" },
+			shouldContinue:     true,
+			wantErr:            true,
+		},
+		{
+			sysVer:             SystemVersion{},
+			getHostOsVersionFn: func(_ types.Host) string { return "1.2.3" },
+			shouldContinue:     true,
+			wantErr:            false,
+		},
+	}
+
+	for _, test := range testData {
+		l := logrus.WithField("test", "test")
+		shouldContinue, err := test.sysVer.IsHostVersionEligible(l, host, test.getHostOsVersionFn)
+
+		if test.wantErr {
+			require.Error(t, err)
+		} else {
+			require.NoError(t, err)
+		}
+
+		require.Equal(t, test.shouldContinue, shouldContinue)
+	}
+}
--- a/internal/updater/versioncompare/compare_linux.go
+++ b/internal/updater/versioncompare/compare_linux.go
@ -0,0 +1,31 @@
+// Copyright (c) 2025 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
+
+//go:build linux
+
+package versioncompare
+
+import (
+	"github.com/elastic/go-sysinfo/types"
+	"github.com/sirupsen/logrus"
+)
+
+// IsHostVersionEligible - Checks whether host OS version is eligible for update. Defaults to true on Linux.
+func (sysVer SystemVersion) IsHostVersionEligible(log *logrus.Entry, _ types.Host, _ func(host types.Host) string) (bool, error) {
+	log.Info("Checking host OS version on Linux. Defaulting to true.")
+	return true, nil
+}
--- a/internal/updater/versioncompare/compare_windows.go
+++ b/internal/updater/versioncompare/compare_windows.go
@ -0,0 +1,31 @@
+// Copyright (c) 2025 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
+
+//go:build windows
+
+package versioncompare
+
+import (
+	"github.com/elastic/go-sysinfo/types"
+	"github.com/sirupsen/logrus"
+)
+
+// IsHostVersionEligible - Checks whether host OS version is eligible for update. Defaults to true on Linux.
+func (sysVer SystemVersion) IsHostVersionEligible(log *logrus.Entry, _ types.Host, _ func(host types.Host) string) (bool, error) {
+	log.Info("Checking host OS version on Windows. Defaulting to true.")
+	return true, nil
+}
--- a/internal/updater/versioncompare/types.go
+++ b/internal/updater/versioncompare/types.go
@ -0,0 +1,29 @@
+// Copyright (c) 2025 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
+
+package versioncompare
+
+import "fmt"
+
+type SystemVersion struct {
+	Minimum string `json:"Minimum,omitempty"`
+	Maximum string `json:"Maximum,omitempty"`
+}
+
+func (sysVer SystemVersion) String() string {
+	return fmt.Sprintf("SystemVersion: Maximum %s, Minimum %s", sysVer.Maximum, sysVer.Minimum)
+}
--- a/internal/user/user.go
+++ b/internal/user/user.go
@ -110,7 +110,7 @@ func New(
 	syncConfigDir string,
 	isNew bool,
 	notificationStore *notifications.Store,
-	getFlagValFn unleash.GetFlagValueFn,
+	featureFlagValueProvider unleash.FeatureFlagValueProvider,
 ) (*User, error) {
 	user, err := newImpl(
 		ctx,
@ -130,7 +130,7 @@ func New(
 		syncConfigDir,
 		isNew,
 		notificationStore,
-		getFlagValFn,
+		featureFlagValueProvider,
 	)
 	if err != nil {
 		// Cleanup any pending resources on error
@ -163,7 +163,7 @@ func newImpl(
 	syncConfigDir string,
 	isNew bool,
 	notificationStore *notifications.Store,
-	getFlagValueFn unleash.GetFlagValueFn,
+	featureFlagValueProvider unleash.FeatureFlagValueProvider,
 ) (*User, error) {
 	logrus.WithField("userID", apiUser.ID).Info("Creating new user")

@ -241,6 +241,7 @@ func newImpl(
 		5*time.Minute,
 		crashHandler,
 		eventSubscription,
+		reporter,
 	)

 	addressMode := usertypes.VaultToAddressMode(encVault.AddressMode())
@ -262,6 +263,8 @@ func newImpl(
 		identityState.Clone(),
 		smtpServerManager,
 		observabilityService,
+		imapServerManager,
+		featureFlagValueProvider,
 	)

 	user.imapService = imapservice.NewService(
@ -282,9 +285,10 @@ func newImpl(
 		user.maxSyncMemory,
 		showAllMail,
 		observabilityService,
+		featureFlagValueProvider,
 	)

-	user.notificationService = notifications.NewService(user.id, user.eventService, user, notificationStore, getFlagValueFn, observabilityService)
+	user.notificationService = notifications.NewService(user.id, user.eventService, user, notificationStore, featureFlagValueProvider, observabilityService)

 	// When we receive an auth object, we update it in the vault.
 	// This will be used to authorize the user on the next run.
@ -739,7 +743,7 @@ func (user *User) protonAddresses() []proton.Address {
 	}

 	addresses := xslices.Filter(maps.Values(apiAddrs), func(addr proton.Address) bool {
-		return addr.Status == proton.AddressStatusEnabled && addr.Type != proton.AddressTypeExternal
+		return addr.Status == proton.AddressStatusEnabled && (addr.IsBYOEAddress() || addr.Type != proton.AddressTypeExternal)
 	})

 	slices.SortFunc(addresses, func(a, b proton.Address) bool {
--- a/internal/user/user_test.go
+++ b/internal/user/user_test.go
@ -28,11 +28,13 @@ import (
 	"github.com/ProtonMail/go-proton-api/server/backend"
 	"github.com/ProtonMail/proton-bridge/v3/internal/certs"
 	"github.com/ProtonMail/proton-bridge/v3/internal/events"
+	"github.com/ProtonMail/proton-bridge/v3/internal/sentry"
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/imapservice"
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/notifications"
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/observability"
 	"github.com/ProtonMail/proton-bridge/v3/internal/services/smtp"
 	"github.com/ProtonMail/proton-bridge/v3/internal/telemetry/mocks"
+	"github.com/ProtonMail/proton-bridge/v3/internal/unleash"
 	"github.com/ProtonMail/proton-bridge/v3/internal/vault"
 	"github.com/ProtonMail/proton-bridge/v3/tests"
 	"github.com/golang/mock/gomock"
@ -110,7 +112,7 @@ func withAccount(tb testing.TB, s *server.Server, username, password string, ali
 	addrIDs := []string{addrID}

 	for _, email := range aliases {
-		addrID, err := s.CreateAddress(userID, email, []byte(password))
+		addrID, err := s.CreateAddress(userID, email, []byte(password), true)
 		require.NoError(tb, err)
 		require.NoError(tb, s.ChangeAddressDisplayName(userID, addrID, email+" (Display Name)"))

@ -150,12 +152,13 @@ func withUser(tb testing.TB, ctx context.Context, _ *server.Server, m *proton.Ma
 	nullEventSubscription := events.NewNullSubscription()
 	nullIMAPServerManager := imapservice.NewNullIMAPServerManager()
 	nullSMTPServerManager := smtp.NewNullServerManager()
+	nullUnleashService := unleash.NewNullUnleashService()

 	user, err := New(
 		ctx,
 		vaultUser,
 		client,
-		nil,
+		sentry.NullSentryReporter{},
 		apiUser,
 		nil,
 		true,
@ -171,9 +174,7 @@ func withUser(tb testing.TB, ctx context.Context, _ *server.Server, m *proton.Ma
 		notifications.NewStore(func() (string, error) {
 			return "", nil
 		}),
-		func(_ string) bool {
-			return false
-		},
+		nullUnleashService,
 	)
 	require.NoError(tb, err)
 	defer user.Close()
--- a/internal/vault/helper.go
+++ b/internal/vault/helper.go
@ -63,6 +63,10 @@ func GetHelper(vaultDir string) (string, error) {
 }

 func SetHelper(vaultDir, helper string) error {
+	if helper == "" {
+		return nil
+	}
+
 	settings, err := LoadKeychainSettings(vaultDir)
 	if err != nil {
 		return err
--- a/pkg/keychain/keychain.go
+++ b/pkg/keychain/keychain.go
@ -82,11 +82,11 @@ func (kcl *List) GetDefaultHelper() string {
 	return kcl.defaultHelper
 }

-// NewKeychain creates a new native keychain.
-func NewKeychain(preferred, keychainName string, helpers Helpers, defaultHelper string) (*Keychain, error) {
+// NewKeychain creates a new native keychain. It also returns the keychain helper used to access the keychain.
+func NewKeychain(preferred, keychainName string, helpers Helpers, defaultHelper string) (kc *Keychain, usedKeychainHelper string, err error) {
 	// There must be at least one keychain helper available.
 	if len(helpers) < 1 {
-		return nil, ErrNoKeychain
+		return nil, "", ErrNoKeychain
 	}

 	// If the preferred keychain is unsupported, fallback to the default one.
@ -97,16 +97,16 @@ func NewKeychain(preferred, keychainName string, helpers Helpers, defaultHelper
 	// Load the user's preferred keychain helper.
 	helperConstructor, ok := helpers[preferred]
 	if !ok {
-		return nil, ErrNoKeychain
+		return nil, "", ErrNoKeychain
 	}

 	// Construct the keychain helper.
 	helper, err := helperConstructor(hostURL(keychainName))
 	if err != nil {
-		return nil, err
+		return nil, preferred, err
 	}

-	return newKeychain(helper, hostURL(keychainName)), nil
+	return newKeychain(helper, hostURL(keychainName)), preferred, nil
 }

 func newKeychain(helper credentials.Helper, url string) *Keychain {
--- a/pkg/keychain/keychain_test.go
+++ b/pkg/keychain/keychain_test.go
@ -120,7 +120,7 @@ func TestIsErrKeychainNoItem(t *testing.T) {
 	helpers := NewList().GetHelpers()

 	for helperName := range helpers {
-		kc, err := NewKeychain(helperName, "bridge-test", helpers, helperName)
+		kc, _, err := NewKeychain(helperName, "bridge-test", helpers, helperName)
 		r.NoError(err)

 		_, _, err = kc.Get("non-existing")
--- a/tests/api_test.go
+++ b/tests/api_test.go
@ -36,6 +36,8 @@ type API interface {
 	GetDomain() string
 	GetAppVersion() string

+	PushFeatureFlag(string)
+
 	Close()
 }

@ -61,6 +63,10 @@ func (api *fakeAPI) GetAppVersion() string {
 	return proton.DefaultAppVersion
 }

+func (api *fakeAPI) PushFeatureFlag(flagName string) {
+	api.Server.PushFeatureFlag(flagName)
+}
+
 type liveAPI struct {
 	*server.Server

--- a/tests/bridge_test.go
+++ b/tests/bridge_test.go
@ -32,6 +32,7 @@ import (
 	"github.com/ProtonMail/proton-bridge/v3/internal/bridge"
 	"github.com/ProtonMail/proton-bridge/v3/internal/events"
 	"github.com/ProtonMail/proton-bridge/v3/internal/kb"
+	"github.com/ProtonMail/proton-bridge/v3/internal/unleash"
 	"github.com/ProtonMail/proton-bridge/v3/internal/vault"
 	"github.com/cucumber/godog"
 	"github.com/golang/mock/gomock"
@ -55,7 +56,7 @@ func (s *scenario) bridgeStops() error {

 func (s *scenario) bridgeVersionIsAndTheLatestAvailableVersionIsReachableFrom(current, latest, minAuto string) error {
 	s.t.version = semver.MustParse(current)
-	s.t.mocks.Updater.SetLatestVersion(semver.MustParse(latest), semver.MustParse(minAuto))
+	s.t.mocks.Updater.SetLatestVersionLegacy(semver.MustParse(latest), semver.MustParse(minAuto))
 	return nil
 }

@ -361,8 +362,8 @@ func (s *scenario) bridgeSendsAnUpdateAvailableEventForVersion(version string) e
 		return errors.New("expected update event to be installable")
 	}

-	if !event.Version.Version.Equal(semver.MustParse(version)) {
-		return fmt.Errorf("expected update event for version %s, got %s", version, event.Version.Version)
+	if !event.VersionLegacy.Version.Equal(semver.MustParse(version)) {
+		return fmt.Errorf("expected update event for version %s, got %s", version, event.VersionLegacy.Version)
 	}

 	return nil
@ -378,8 +379,8 @@ func (s *scenario) bridgeSendsAManualUpdateEventForVersion(version string) error
 		return errors.New("expected update event to not be installable")
 	}

-	if !event.Version.Version.Equal(semver.MustParse(version)) {
-		return fmt.Errorf("expected update event for version %s, got %s", version, event.Version.Version)
+	if !event.VersionLegacy.Version.Equal(semver.MustParse(version)) {
+		return fmt.Errorf("expected update event for version %s, got %s", version, event.VersionLegacy.Version)
 	}

 	return nil
@ -391,8 +392,8 @@ func (s *scenario) bridgeSendsAnUpdateInstalledEventForVersion(version string) e
 		return errors.New("expected update installed event, got none")
 	}

-	if !event.Version.Version.Equal(semver.MustParse(version)) {
-		return fmt.Errorf("expected update installed event for version %s, got %s", version, event.Version.Version)
+	if !event.VersionLegacy.Version.Equal(semver.MustParse(version)) {
+		return fmt.Errorf("expected update installed event for version %s, got %s", version, event.VersionLegacy.Version)
 	}

 	return nil
@ -483,3 +484,25 @@ func (s *scenario) bridgeSMTPPortIs(expectedPort int) error {

 	return nil
 }
+
+func (s *scenario) bridgeLegacyUpdateKillSwitchEnabled() error {
+	unleash.ModifyPollPeriodAndJitter(5*time.Second, 0)
+	s.t.api.PushFeatureFlag(unleash.UpdateUseNewVersionFileStructureDisabled)
+	return nil
+}
+
+func (s *scenario) bridgeLegacyUpdateEnabled() error {
+	return eventually(func() error {
+		res := s.t.bridge.GetFeatureFlagValue(unleash.UpdateUseNewVersionFileStructureDisabled)
+		fmt.Println("RES", res)
+		if res != true {
+			return fmt.Errorf("expected the %v kill-switch to be enabled", unleash.UpdateUseNewVersionFileStructureDisabled)
+		}
+		return nil
+	})
+}
+
+func (s *scenario) bridgeChecksForUpdates() error {
+	s.t.bridge.CheckForUpdates()
+	return nil
+}
--- a/tests/ctx_reporter_test.go
+++ b/tests/ctx_reporter_test.go
@ -89,8 +89,11 @@ func (r *reportRecorder) close() {
 }

 func (r *reportRecorder) assertEmpty() {
-	if !r.skipAssert {
-		r.assert.Empty(r.reports)
+	if !r.skipAssert && len(r.reports) > 0 {
+		for _, report := range r.reports {
+			// Sentry reports with failed syncs are expected, mostly due to sync context cancellations.
+			r.assert.Equal(report.message, "Failed to sync, will retry later")
+		}
 	}
 }

@ -143,6 +146,11 @@ func (r *reportRecorder) ReportMessageWithContext(message string, context report
 	return nil
 }

+func (r *reportRecorder) ReportWarningWithContext(message string, context reporter.Context) error {
+	r.add(false, message, context)
+	return nil
+}
+
 func (r *reportRecorder) ReportExceptionWithContext(data any, context reporter.Context) error {
 	if context == nil {
 		context = reporter.Context{}
--- a/tests/features/bridge/updates_legacy.feature
+++ b/tests/features/bridge/updates_legacy.feature
@ -1,23 +1,34 @@
 Feature: Bridge checks for updates
+  Background:
+    Given the legacy update kill switch is enabled
+
  Scenario: Update not available
    Given bridge is version "2.3.0" and the latest available version is "2.3.0" reachable from "2.3.0"
    When bridge starts
+    And bridge verifies that the legacy update is enabled
+    And bridge checks for updates
    Then bridge sends an update not available event

  Scenario: Update available without automatic updates enabled
    Given bridge is version "2.3.0" and the latest available version is "2.4.0" reachable from "2.3.0"
    And the user has disabled automatic updates
    When bridge starts
+    And bridge verifies that the legacy update is enabled
+    And bridge checks for updates
    Then bridge sends an update available event for version "2.4.0"

  Scenario: Update available with automatic updates enabled
    Given bridge is version "2.3.0" and the latest available version is "2.4.0" reachable from "2.3.0"
    When bridge starts
+    And bridge verifies that the legacy update is enabled
+    And bridge checks for updates
    Then bridge sends an update installed event for version "2.4.0"

  Scenario: Manual update available with automatic updates enabled
    Given bridge is version "2.3.0" and the latest available version is "2.4.0" reachable from "2.4.0"
    When bridge starts
+    And bridge verifies that the legacy update is enabled
+    And bridge checks for updates
    Then bridge sends a manual update event for version "2.4.0"

  Scenario: Update is required to continue using bridge
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Atanas Janeshliev	4cc2ded001	chore: Kanmon Bridge 3.21.2 changelog.	2025-07-07 11:34:42 +02:00
Atanas Janeshliev	15880dfe19	fix(BRIDGE-406): fixed faulty certificate chain validation logic; made certificate pin checks exclusive to leaf certs;	2025-07-04 15:19:44 +02:00
Atanas Janeshliev	e9ea976773	chore: Kanmon Bridge 3.21.1 changelog.	2025-06-11 16:15:53 +02:00
Atanas Janeshliev	a00af3a398	feat(BRIDGE-383): Internal mailbox conflict resolution extended; Minor alterations to mailbox conflict pre-checker	2025-06-11 16:11:20 +02:00
Atanas Janeshliev	50ab740b92	chore: Kanmon Bridge 3.21.0 changelog.	2025-06-05 15:45:27 +02:00
Atanas Janeshliev	39f2362996	feat(BRIDGE-379): mailbox pre-checker on startup & conflict resolver for bridge internal mailboxes; TODO potentially add this for system mailboxes as well	2025-06-05 14:34:29 +02:00
Atanas Janeshliev	d2742c81e5	feat(BRIDGE-376): catch gluon errors related to label uniqueness constrainst...	2025-06-05 14:34:29 +02:00
Atanas Janeshliev	9cb914cf13	fix(BRIDGE-377): Correct label field usage on label update handler	2025-06-05 14:34:29 +02:00
Atanas Janeshliev	4088cf18c3	feat(BRIDGE-373): extend label conflict resolver logging & report sync errors to sentry	2025-06-05 14:34:29 +02:00
Atanas Janeshliev	c02bae5eb2	fix(BRIDGE-378): Fix incorrect field usage for system mailbox names	2025-06-03 17:36:58 +02:00
Atanas Janeshliev	2aa8acfb5b	chore: changes to reconcile release/jubilee with dev	2025-05-28 16:56:28 +02:00
Atanas Janeshliev	8109b384c5	fix(BRIDGE-362): added label conflict reconciliation logic	2025-05-28 16:56:07 +02:00
Atanas Janeshliev	6d79ad3e41	chore: Jubilee Bridge 3.20.1 changelog.	2025-05-28 16:53:23 +02:00
Atanas Janeshliev	5d93ee0cfc	chore: Jubilee Bridge 3.20.0 changelog.	2025-05-28 16:53:23 +02:00
Atanas Janeshliev	c3e2201945	feat(BRIDGE-366): Kill switch support for IMAP IDLE	2025-05-28 09:53:45 +02:00
Atanas Janeshliev	89da7335b6	feat(BRIDGE-363): Observability metrics for IMAP connections; minor unleash service refactor;	2025-05-16 15:28:53 +02:00
Atanas Janeshliev	a305ee1113	chore: Infinity Bridge 3.19.0 changelog.	2025-04-24 11:13:17 +02:00
Atanas Janeshliev	e38f7748d0	chore: bump GPA	2025-04-22 12:41:13 +00:00
Atanas Janeshliev	92b2024e3e	chore(BRIDGE-352): bump go to 1.24.2	2025-04-17 14:06:54 +00:00
Atanas Janeshliev	37a8fc95d2	chore(BRIDGE-353): update x/net package to 0.38.0	2025-04-17 10:48:31 +02:00
Atanas Janeshliev	0c63533aa7	fix(BRIDGE-351): allow draft creation and import to BYOE addresses in combined mode	2025-04-15 17:26:14 +02:00
Atanas Janeshliev	af98bc2273	fix(BRIDGE-301): don't use external, non-BYOE addresses for imports	2025-04-10 09:51:31 +00:00
Atanas Janeshliev	b37f2d138a	feat(BRIDGE-348): display BYOE addresses in Bridge	2025-04-10 10:06:40 +02:00
Atanas Janeshliev	7831a98e6c	chore(BRIDGE-346): silence http/net vulnerability	2025-04-09 10:49:34 +02:00
Atanas Janeshliev	4d415675e0	fix(BRIDGE-341): replace go-autostart with fork; added ability to create shortcuts with unicode chars	2025-04-02 11:56:58 +00:00
Atanas Janeshliev	291f44d1b5	fix(BRIDGE-332): filter new line characters from username and password fields in GUI	2025-04-01 14:37:18 +02:00
Atanas Janeshliev	a4b315d67a	fix(BRIDGE-336): check and create all labels in Gluon on Bridge start	2025-03-25 15:24:59 +01:00
Jakub Cuth	a15d4eb3ef	ci: update CODEOWNERS	2025-03-24 15:38:03 +01:00
Atanas Janeshliev	4e764fe93d	feat(BRIDGE-340): additional logging for label operations & bad events	2025-03-24 14:30:19 +01:00
Atanas Janeshliev	df409925ec	fix(BRIDGE-335): store last sucessfully used keychain helper as user preference	2025-03-19 15:10:09 +01:00
Atanas Janeshliev	e68f3441d7	fix(BRIDGE-196): bump badssl public key	2025-03-19 10:00:23 +00:00
Atanas Janeshliev	899d3293bc	feat(BRIDGE-324): added a log entry for the vault key hash	2025-03-18 11:21:12 +00:00
Atanas Janeshliev	c66f0b800a	fix(BRIDGE-333): ignore unkown label IDs during synchronization	2025-03-17 10:43:26 +01:00
Atanas Janeshliev	b9c75d02b2	chore: stabilize windows tests	2025-03-14 11:56:42 +01:00
Atanas Janeshliev	4b91e66505	chore(BRIDGE-315): remove silenced vulns	2025-03-06 14:49:03 +00:00
Atanas Janeshliev	0cbcd0bf13	fix(BRIDGE-329): fix menu bar icons not displayin on macOS	2025-03-06 15:10:52 +01:00
Atanas Janeshliev	5c12b00e70	chore: Helix Bridge 3.18.0 changelog.	2025-03-06 10:37:52 +01:00
Atanas Janeshliev	6e7cdfcd68	feat(BRIDGE-316): Changes required for Qt 6.8.2 bump; bumped go to 1.24.0; changes to OS bundler configs; golangci-lint bump;	2025-03-05 14:27:33 +01:00
Atanas Janeshliev	a75f84742b	chore: remove redundant log entry	2025-02-24 10:58:16 +01:00
Atanas Janeshliev	f4ddf43ac7	chore: Grunwald Bridge 3.17.0 changelog.	2025-02-18 17:11:46 +01:00
Atanas Janeshliev	da0f51ce5f	feat(BRIDGE-309): Update to the bridge updater logic corresponding to the version file restructure	2025-02-17 15:43:15 +00:00
Atanas Janeshliev	d711d9f562	feat(BRIDGE-154): include access token when refreshing	2025-02-17 15:10:05 +01:00