I have an old mail server that I recently replaced.
The replacement is delivering mail as expected, but there is an odd quirk. I have a variety of aliases that deliver mail to a list of people. When user@domain.com sends an e-mail via Outlook to list@domain.com, there is a mapping for that Mail-User to an external address called list@mail.domain.com, so the To: gets rewritten and delivered to our mail server. When newserver.domain.com gets the message, it accepts it and delivers it, but rewrites the To: header to list@newserver.domain.com.
The issue with this is that it breaks the reply-to because it expects @domain.com and @mail.domain.com. How can I prevent this from happening? I have a CNAME in place that mail.domain.com points to newserver.domain.com, which makes me think it is mapping it from DNS somehow. Can I prevent this, or at least force it to use mail.domain.com or domain.com instead of newserver?
Example of the sendmail -bt /try esmtp test: