by rob » Thu Oct 30, 2008 10:38 am
Its possible an AV filter (most likely), firewall or SPAM filter are intercepting the port 25 requests and preventing them reaching the mail server. I would recommend you disable any automated scannin software temporarily to see if the issue resolves its self (you may need to reload the mail server or even reboot the server). It is also possible a router is preventing your SMTP connections and so it would be worth checking your router/modem settings.