Originally Posted by till
Have you forwarded the smtp port from your router to your server and made sure its not blocked by a firewall?
Have you checked that your provider does not block port 25?
Yes, port 25 has been forwarded from the router and firewall to the server and vise-versa. My users can access their emails, unfortunately sending and receiving does not work properly. I also wonder why i can receive the automatic emails from my guestbook provider (third party), once a message is posted on our guestbook. I tried sending emails to yahoo and other corporate emails outside our domain, but sending fails....
As of the moment, I configured my servers back to its original network setup, and I will try to configure a new mail server, which will be installed behind the said Anti-Virus and Anti-Spam router/firewall and see if it works.