I have a Small Business Server 2003, which I installed, mostly with the recommendations and defaults. The server was working great for about two months, when all of the sudden two days ago, the emails stopped getting sent. No settings have changed. Here is what I've done and noticed:
We made sure the DNS is correct.
NSLOOKUP looks good.
The log file for Exchange has doubled in size in the last two days, however, I haven't tried to search or interpret it.
In the Exchange System Manager, Under Servers > Server1 > Queues, I can see a list of about 35 mail servers that are showing: "The remote server did not respond to a connection attempt." I have tried to force a connection, it's not happening.
I tried to telnet into the remote server's port 25, and they fail to connect.
This server is behind a SonicWALL firewall, that is open to allow SMTP port 25. Remember, this worked until two days ago, then it mysteriously stopped working.
Please urgently reply to this question.