I am in the process of migrating to Exchange 2013 (from 2010)
I have installed 2 2013 servers (1 cas and 1 mbx). I created a database and migrated some pilot users. The users have been able to work for about a week without issues. But since last weekend, they don't receive incoming mail from external domains. Internal incoming mail as well as all outgoing mail works fine.
I have pinpointed the issue to the following: The receive connector listenes to port 25 (I can telnet the port). But it only responds (220 <CASservername>.<domain>.local Microsoft ESMTP MAIL Service ready at Mon, 3 Jun 2013 14:33:38 +0200)
It does not respond to a telnet session from any other location (e.g. the edge server or a server in the same subnet). The connection is established but no response is shown. As soon as the first character is typed, the connection is broken.
ExRCA showes "A connection was established but a banner was never received" so this points to the same issue.
To recap: telnet <ipaddress CAS> 25 does give response from CAS server itself, but not from any other location.
I allready tested with the FW off. AV is SCEP 2012.
How to troubleshoot this issue? The only thing that has changed over the weekend, is the installation of the latest security patches.
Regards,
Stephan
You know you're an engineer when you have no life and can prove it mathematically