Hello everyone. This is only my second time posting, but I have been wrapping my brain around trying to find a solution to this problem. I have Exchange 2003 and some of my users have been getting undeliverable. I have scowered this site and couldnt find someone with the same problem as me, but this is what we get.
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<mail.ppmco.com #5.5.0 smtp;550-mailinc25: Host <Our IP Address is here for our firewall>: No email accepted from this host>
The IP address is the IP address of our Firewall. Its our external address. We dont get this on all emails, just certains domains that we send too. I have already done an nslookup and have looked at dnsstuff.com. All appears to be ok. We do use appriver.com as our filtering. All emails that go external are routed through appriver, then out. Vise-Versa for when mail comes in. Any clues or help would be appreciated!! :P