I have been working on this problem for a few days, and I almost have it figured out. When sending email a few domains will instantly bounce back a NDR with the error:"The following organization rejected your message: ESMTP" I thought it was a blacklist problem, checked, and everything is clear. Checked Exchange and it has the error "#554 Transaction Failed Spam Message not queued."
I think I have this tracked down to a mismatch between my FQDN and/or DNS so that email fails a reverse lookup by the receivers server, which then bounces it as spam. The problem is I'm not sure what is supposed to match.
My setup: (Which I inherited from a retired Admin :) )
- Exchange 2007 is running on the DC named Domain-Server.abm1.local
- Under Exchange / Organizational Config / Hub Transport / Send Connectors, my FQDN is exchange.abm1.com.
- Under Exchange / Server Config / Hub Transport / Receive Connectors, my FQDN is exchange.abm1.com.
- In my DNS I have exchange.abm1.com listed under Forward Lookup Zones with a ns of domain-server.abm1.local and an A record of 172.16.1.2.
- Under Reverse lookup I have 172.16.1.2 pointing to domain-server.abm1.local.
- Ehlo command to the mail server returns the name of exchange.abm1.com
What am I missing?