Incoming mail to wrong server
We have setup the Open Source version which appears to be running correctly with the exception of incoming mail.
Mail can go out to other domains, but the incoming mail is being grabbed by our other server which hosts the mail of the domain the server is part of.
i.e. mail server A hosts the main domain mail and server B hosts another domain but is part of A's hosted domain (A.domain1.com and B.domain1.com while B hosts domain2.com)
I think this may have to do with a dns misconfiguration but am not sure where to start looking.
We have a DNS server, and the relevant records are pointing to B for the mail of domain2.
If anyone can advise what checks I can run to determine the problem?