The hostname that resolves to the Internet (WAN) IP of your mail server. For example, if you are using Dynamic DNS and your hostname is
For the port, you enter the port number you've forwarded to your email server. Generally this should be 25 unless your ISP blocks it.
If you haven't already configured a Dynamic DNS hostname and forwarded ports then please work through this sticky.
answered Feb 21 '12 at 07:01 AM
Cry Havok ♦