That’s very strange. When I send an outbound message to example@gmail.com, from my mailcow server with the address example@mydomain.com it goes through normally and I receive it in my gmail inbox. I see the following corresponding event in the postfix log:
F408856A19F: replace: header Received: from a9f19bf81508 (mailcowdockerized-sogo-mailcow-1.mailcowdockerized_mailcow-network [172.22.1.248])??(Authenticated sender: example@mydomain.com)??by mail.mydomain.com (Postcow) from mailcowdockerized-sogo-mailcow-1.mailcowdockerized_mailcow-network[172.22.1.248]; from=<example@mydomain.com> to=<example@gmail.com> proto=ESMTP helo=<a9f19bf81508>: Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPA id F408856A19F??for <example@gmail.com>; Fri, 29 Mar 2024 12:44:58 -0400 (EDT)
and
F408856A19F: to=<example@gmail.com>, relay=smtp.sendgrid.net[18.223.240.158]:587, delay=9.6, delays=8.4/0.03/1.1/0.04, dsn=2.0.0, status=sent (250 Ok: queued as _sg6eo83Sq-z--uzkbGLYQ)
If I reply to that email from my gmail inbox, it never arrives in my mailcow mailbox, and that’s when I get this event in the postfix log:
55A1556A19A: to=<example@gmail.com>, relay=smtp.sendgrid.net[18.223.240.158]:587, delay=0.12, delays=0.01/0/0.08/0.03, dsn=5.0.0, status=bounced (host smtp.sendgrid.net[18.223.240.158] said: 550 The from address does not match a verified Sender Identity. Mail cannot be sent until this error is resolved. Visit https://sendgrid.com/docs/for-developers/sending-email/sender-identity/ to see the Sender Identity requirements (in reply to end of DATA command))
and
2CAEF56A1B6: to=<example@mydomain.com>, relay=smtp.sendgrid.net[18.223.240.158]:587, delay=13, delays=11/0.06/2.4/0.06, dsn=5.0.0, status=bounced (host smtp.sendgrid.net[18.223.240.158] said: 550 The from address does not match a verified Sender Identity. Mail cannot be sent until this error is resolved. Visit https://sendgrid.com/docs/for-developers/sending-email/sender-identity/ to see the Sender Identity requirements (in reply to end of DATA command))
I am not sending an outbound message when I see these in the log, but I am replying to the test message I sent from my gmail address, so I’m not sure why these appear as outbound emails. Is there a different log I should be examining?