I have looked throughout EE and found some questions that come close to my problem but don’t fix it for me.
My problem is: I have an MS server running Exchange and DNS services (LAN address 192.168.11.3) behind a DSL wireless router. The router has a LAN address of 192.168.11.1 and a WAN address that is supplied dynamically by the service provider (I don't enter any IP info for WAN side). I have setup NAT on the router to forward port 25 traffic to the LAN address of the Exchange server.
I have the MX record registered with a domain registration company.
I am able to send emails from my Exchange server, but not receive.
If I try an SMTP session from outside I get ‘Connection refused’.