Subject: test
From: test1@test
To: test2@test
Message-ID: <1@test>
Content-Type: multipart/mixed; boundary="abc"

--abc
Content-Type: text/plain; charset=utf-8

test1

--abc
Content-Type: image/jpeg; name="test.jpg"
Content-Disposition: attachment; filename="test.jpg"
Content-Transfer-Encoding: base64
Content-ID: <1>
X-Attachment-Id: 1

dGVzdGltYWdl

--abc--