Every so often external e-mail stops being received. The event logs on the mail server are fine, all services are running, it will send all messages out fine, and receive internal emails, but it WILL NOT receive any external e-mail. All of the exchange services on the mail server have been restarted, no new or additional software has been installed. The only way we're able to start receiving external e-mail again is to reboot the entire server. Anyone have any ideas? Thanks.

Is the server in the DMZ, behind a router or is it dual homed? If it's in the DMZ, the next time it happens, run netstat -an to see if it has lost it's external IP address. If it's dual homed, then one of the NICs is losing it's connection. If it's behind a router, I suspect it's something w/ port fowarding.

"If it's behind a router, I suspect it's something w/ port fowarding." I would doubt that. Firewalls don't spontaenously have rule changes. Next time it happens, attempt to telnet to the mail server to port 25 on the internet facing NIC (if multihomed) and send an email to someone. http://support.microsoft.com/?kbid=... Please help survivors of Hurricane Katrina! www.redcross.org

Thanks for the help guys, but what about after telnetting to the mail server & sending an e-mail? I'm missing something here.

Are you able to do so? If so, that would mean the problem is not your mail server most likely. Please help survivors of Hurricane Katrina! www.redcross.org

Don't forget to run netstat -an on the server when it loses the connection.