From: Sartak <sartak@example.com>
Subject: Fwd: This is a banana
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary=xyzzy

--xyzzy
Content-Type: multipart/alternative; boundary=plugh

--plugh
Content-Type: text/plain

Foo.

--plugh
Content-Type: text/html

Bar.

--plugh--

--xyzzy
Content-Type: application/pdf
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename=banana.pdf

IyEvdXNyL2Jpbi9lbnYgcGVybAp1c2Ugc3RyaWN0Owp1c2Ugd2FybmluZ3M7CgpkaWUgImJhbmFu
YVxuIjsKCg==

--xyzzy--