I am absolutely stumped on this one. We can send and receive email with no problems with the exception of *receiving* mail from a particular domain.
We are running a Postfix mail server with the spamd (spamasassin daemon) running. Mail on THEIR domain is sent from an Exchange 2000 server. All I see in our logs is:
Oct 24 15:18:57 localhost postfix/smtpd[XXXX]: connect from theirserver.theirdomain.com[theirIP]
Oct 24 15:19:05 localhost postfix/smtpd[XXXX]: disconnect from theirserver.theirdomain.com[theirIP]
Again, it is ONLY mail from their domain that we have a problem receiving. Likewise, our domain is the only one that they have trouble sending to. In their logs, all they have is a "message time-out" error.
I, at first thought it might be an MX record issue because they just changed the domain naming scheme of their servers....I'm not sure this possibility has been completely ruled out. I would think, though, that if it was an MX issue, their domain would have problems sending mail to more domains than just ours.
This leads me to believe it is something on our end, yet we don't have any other problems sending and receiving to and from any other domains.
Again, we can send mail TO this domain, but cannot receive mail FROM this domain.
I have whitelisted their domain name, ip and domain suffix in postfix and spam assassin.
I am so confused. I hope someone can help.