To reproduce: 1) Set up at least two mail accounts 2) Compose a message From: the second account To: Echo@TU-Berlin.DE (Testcase) 3) Choose to send message later 4) Send unsent messages 5) Get all new messages The testcase shows the automatic reply from Echo@TU-Berlin.DE being sent to the first mail account because of Mozilla using the first mail account as smtp-envelope. If the testcase is changed and the message is not send later but directly from the compose window Mozilla uses the correct address as smtp-envelope.

*** This bug has been marked as a duplicate of 59548 ***