diff --git a/internal/smtp/preferences.go b/internal/smtp/preferences.go
index a02c59c2..28dead1f 100644
--- a/internal/smtp/preferences.go
+++ b/internal/smtp/preferences.go
@@ -95,11 +95,13 @@ func (b *sendPreferencesBuilder) shouldEncrypt() bool {
 	return false
 }
 
-func (b *sendPreferencesBuilder) withSign(v bool) {
+func (b *sendPreferencesBuilder) withSign() {
+	v := true
 	b.sign = &v
 }
 
-func (b *sendPreferencesBuilder) withSignDefault(v bool) {
+func (b *sendPreferencesBuilder) withSignDefault() {
+	v := true
 	if b.sign == nil {
 		b.sign = &v
 	}
@@ -256,7 +258,7 @@ func (b *sendPreferencesBuilder) setInternalPGPSettings(
 
 	// We always encrypt and sign internal mail.
 	b.withEncrypt(true)
-	b.withSign(true)
+	b.withSign()
 
 	// We use a custom scheme for internal messages.
 	b.withScheme(pmInternal)
@@ -367,7 +369,7 @@ func (b *sendPreferencesBuilder) setExternalPGPSettingsWithWKDKeys(
 
 	// We always encrypt and sign external mail if WKD keys are present.
 	b.withEncrypt(true)
-	b.withSign(true)
+	b.withSign()
 
 	// If the contact has a specific Scheme preference, we set it (otherwise we
 	// leave it unset to allow it to be filled in with the default value later).
@@ -402,7 +404,7 @@ func (b *sendPreferencesBuilder) setExternalPGPSettingsWithoutWKDKeys(
 
 	// Sign must be enabled whenever encrypt is.
 	if vCardData.Sign || vCardData.Encrypt {
-		b.withSign(true)
+		b.withSign()
 	}
 
 	// If the contact has a specific Scheme preference, we set it (otherwise we
@@ -468,10 +470,12 @@ func (b *sendPreferencesBuilder) setEncryptionPreferences(mailSettings pmapi.Mai
 	// mail setting "Sign External messages". Otherwise we keep the defined value
 	// unless it conflicts with the encrypt flag (we do not allow to send
 	// encrypted but not signed).
-	b.withSignDefault(mailSettings.Sign > 0)
+	if mailSettings.Sign > 0 {
+		b.withSignDefault()
+	}
 
 	if b.shouldEncrypt() {
-		b.withSign(true)
+		b.withSign()
 	}
 
 	// If undefined, default to the user mail setting "Default PGP scheme".
diff --git a/internal/smtp/preferences_test.go b/internal/smtp/preferences_test.go
index d08f3400..f36133d4 100644
--- a/internal/smtp/preferences_test.go
+++ b/internal/smtp/preferences_test.go
@@ -56,7 +56,7 @@ func TestPreferencesBuilder(t *testing.T) {
 			wantEncrypt:   true,
 			wantSign:      true,
 			wantScheme:    pmapi.InternalPackage,
-			wantMIMEType:  "multipart/mixed",
+			wantMIMEType:  "text/html",
 			wantPublicKey: testPublicKey,
 		},
 
@@ -71,7 +71,7 @@ func TestPreferencesBuilder(t *testing.T) {
 			wantEncrypt:   true,
 			wantSign:      true,
 			wantScheme:    pmapi.InternalPackage,
-			wantMIMEType:  "multipart/mixed",
+			wantMIMEType:  "text/plain",
 			wantPublicKey: testPublicKey,
 		},
 
@@ -86,7 +86,7 @@ func TestPreferencesBuilder(t *testing.T) {
 			wantEncrypt:   true,
 			wantSign:      true,
 			wantScheme:    pmapi.InternalPackage,
-			wantMIMEType:  "multipart/mixed",
+			wantMIMEType:  "text/html",
 			wantPublicKey: testPublicKey,
 		},
 
@@ -102,7 +102,7 @@ func TestPreferencesBuilder(t *testing.T) {
 			wantEncrypt:   true,
 			wantSign:      true,
 			wantScheme:    pmapi.InternalPackage,
-			wantMIMEType:  "multipart/mixed",
+			wantMIMEType:  "text/html",
 			wantPublicKey: testPublicKey,
 		},