Our office has a Win2K3 DC/DNS server and another Win2K3 server hosting MS Exchange 2003.
Recently our users have been getting some undeliverable mail messages from our MX Exchange 2003 Administrator. Specifically 4.4.7 and 5.5.0 error messages. What’s odd is that some e-mails go out fine, but others don’t.
We’ve checked the firewall logs and it appears that port 25 SMTP requests are repeatedly being sent by the mail server to the domains (or IP addresses seen in the logs) we have been having trouble with.