I have an exchange 2003 sp2 server that has been running smoothly for a few years now. As of a couple days ago, I am no longer able to send email to one particular domain. I have done a ton of troubleshooting but the result of one of my tests is confusing to me.
All email is stuck in the queue on my server. So I figured I would telnet into the remote server to verify connectivity. I am able to telnet in, but I cannot get a response from the server. When I telnet in, I see the 220 mail.domain.com ESMTP...... Here I would normally type ehlo or helo, but when you do that and hit enter, it just hangs there and after a few minues comes back to say the connection to host has been lost.
The even more odd thing is that it is happening on their end as well. They are not able to send my domain any email. This was working smoothly 2 days ago and no changes have been made at either site.
Since I was able to telnet on port 25 I have pretty much ruled out a firewall.
I have ran smtpdiag and all passes except the part where it is trying to connect to the mailserver.
My domain is not using a smart host to send email, but has a front end server to receive email. I believe the remote domain has a front end server to send and receive.
All other email to every other domain is working like a champ.
Any help at all would be great!!!