From: sender@example.com
To: recipient@example.com
Subject: Test inline image proper
MIME-Version: 1.0
Content-Type: multipart/related; boundary="boundary123"
--boundary123
Content-Type: text/html; charset=utf-8
--boundary123
Content-Type: image/png; name="test1.png"
Content-Disposition: inline; filename="test1.png"
Content-ID:
Content-Transfer-Encoding: base64
iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP8/5+hHgAHggJ/PchI7wAAAABJRU5ErkJggg==
--boundary123--