Content-Type: multipart/mixed; boundary="===============3209040583106423479=="
MIME-Version: 1.0
From: test@example.org
To: test@example.org
Date: Thu, 26 Sep 2019 15:52:32 -0000
Subject: Test message
Message-ID: <156951315267.43830.14912869070271436609@example.org>

--===============3209040583106423479==
Content-Type: image/gif
MIME-Version: 1.0
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="Transparent.gif"

R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7

--===============3209040583106423479==