Some of the exchange users at my location are complaining anout the nod-delivery of the mails with following error.
the following recipient(s) could not be reached:
on 5/25/2009 12:20 PM
You do not have permission to send to this recipient. For assistance, contact your system administrator. <mydomain-name.in #5.7.1 smtp;554 5.7.1 This message has been blocked because the return email domain is invalid.(failed to obtain DNS record for domain mydomain-name.in)>
But the thing is that they do not get this error every time they send a mail. They face this issue only for some remote domains. I have verified and found A, MX and PTR records for my mail server are in place. One thing that is troubling me is internal FQDN of my mail server is "abc-mail.mydomain.in" whereas external FQDN for mail server is "mail.mydomain.in". The MX record visible to the world is obviously pointing to "mail.mydomain.in" but corresponding PTR record is pointing to "abc-mail.mydomain.in". It seems the setup was done this way because we had standard naming convention for servers but our DNS hosting service provider does not allow Hyphen to be present in the A record. So, external FQDN was different from internal. Please let me know if it has anything to do with this problem! If not then what can I do to get it resolved.