Telnet is a good test of whether a domain or IP is the correct one for you to use. If this doesn't come back with a welcome message from AMS then you probably need to alter this to get it working. Either your domain IPs, router or firewall aren't allowing the connections properly. If you use an Internet IP not an internal network IP then this should work from anywhere. Also, make sure you don't have IP restrictions on the services that are stopping the connections. Also, SPAM transaction delays on welcome message could delay the welcome message so check for that too.
If you send me your domain (i.e. the bit after the @ in your email addresses) to
chris@code-crafters.com I'll check the MX records and connections for you.
1) You should have at least one domain you have purchased. Or you can get a free one from
http://www.no-ip.com.
2) You then need to setup your domain as follows:
domain.com
A = your website IP
MX = mail.domain.com
mail.domain.com
A = your mail server Internet IP
3) Next you need to forward ports 25, 143, 110 etc on your router to your mail server LAN IP which needs to be a static IP.
4) Let any mail server ports through any server side firewalls.
5) Make sure no other mail server is running on the AMS computer (using telnet or the status page of the admin interface).