Received: We have to put a Received header here. Otherwise, the message would be ignored because DC thinks it's a draft, and the test fails. Alternatively, we could configure the Sentobox folder in the test. MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="=_3293d145f71bf71c4bb97415536759d6" Date: Mon, 13 Dec 2021 12:33:58 +0100 From: Anonymous_1 To: Anonymous_2 Subject: Test message Return-Receipt-To: Anonymous_1 Disposition-Notification-To: Anonymous_1 Message-ID: X-Sender: alice@example.org User-Agent: Posteo Webmail --=_3293d145f71bf71c4bb97415536759d6 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII This is a test! Best regards --=_3293d145f71bf71c4bb97415536759d6 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=UTF-8 This is a test!

Best regards --=_3293d145f71bf71c4bb97415536759d6--