From: Moderator-Address <moderator>
Content-Type: multipart/digest; boundary=1;


--1

From: someone-else <someone@else>
Subject: my opinion

This is my opinion
--1

From: another one <another@one>
Subject: i disagree

Not agreeing one bit!
--1

From: attachment <attachment@user>
Subject: funny hat
Content-Type: multipart/mixed; boundary=2

--2
Content-Type: text/plain
Content-Transfer-Encoding: binary

Lovely attachment for you
--2
Content-Type: application/octet-stream; disposition=attachment; name="test.txt"
Content-Transfer-Encoding: binary

Foobar
--2--
--1--