External Email Delivery Failure/Delay
Posted on 2010-01-05
I am able to receive emails from external mail servers with no problems. However, emails from users on my network are not being accepted by the destination mail servers. I am able to look at my firewall logs and network captures of the traffic from my mail server. Traffic is is leaving my mail server and connecting to the external mail servers on port 25. In the packet capture the my mail server is only making a SYN connection to the external mail servers and they are not responding.
Its as if the external mail servers don't want to talk to my exchange server. I checked to see if my IP address was blacklisted and it is not.
Could it be a configuration error with the exchange server?