To test connectivity to the server via a specific port, use the telnet command from a command prompt on your computer.
To telnet to the server, greatmail.com through port 2500:
- Go to Start/Run.
- Type cmd and click OK.
- In the command window that appears, type:
telnet greatmail.com 2500
- Hit enter
- You should see something like:
220 greatmail3.nmsrv.com ESMTP
If you do not see any 220 communication with the server to which you are trying to connect, there is likely a firewall or networking issue preventing your connection to the server on the specified port.