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: quoted-printable

body

--longrandomstring
Content-Transfer-Encoding: quoted-printable

some other part of the message
--longrandomstring--
.