Content-Type: multipart/mixed; boundary=longrandomstring
From: Sender <sender@pm.me>
To: Receiver <receiver@pm.me>


This is a multi-part message in MIME format.
--longrandomstring
Content-Transfer-Encoding: base64

Ym9keQ==
--longrandomstring
Content-Transfer-Encoding: base64
Content-Type: application/octet-stream

aWYgeW91IGFyZSByZWFkaW5nIHRoaXMsIGhpIQ==
--longrandomstring--
.