+ 0 Votes Need a bit more information... jpeoples 7 years ago Couple of questions about your configuation. Does your firewall have a DMZ or are you using NAT for the public address of the front end server? Do you have a standing ping running to the Mail Svr? If so how long has that ping been running, i.e. do you keep it up all the time or do you only turn it on when you're having problems? Do you have logging turned on in your firewall? If so is anything being reported there? Have you tried doing a trace in either direction? While the server is in accessable ask one of your friends to send you mail using another ISP or a web mail provider. Check to see if the server receives the message during that time. Most firewalls have a default configuration that prevents pinging the unsecure interface because of DoS attacks yours might be seeing the standing ping as such. Let me know if you need more help.