I don't completely understand everything reguarding the MTA, but I have a possible installation mistake.
The question: Does the hostname given by the MTA on connect have to be routeable back to the server for some reason?
When I installed Zimbra, I gave it the internal hostname for the server (eg, a.domain.com). However, I realized later I really wanted Zimbra to work as mail.domain.com. All of my outside DNS entries are set up for mail.domain.com. My internal DNS server (because I am behind a NAT) is also configured for a.domain.com. Mail seems to be sent and received just find. When a server connects to my MTA, it gives its hostname as a.domain.com - which cannot be routed back using a DNS lookup.
Due to the way I have the server set up, I would really prefer to not set up the DNS entry for a.domain.com.
A followup question: If this could be a problem, should I try to reconfigure Zimbra to use the mail.domain.com as explained in the Wiki?
- Phil DeJarnett