How do I test my connectivity to the server through a specific port number?

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:

  1. Go to Start/Run.
  2. Type cmd and click OK.
  3. In the command window that appears, type:
    telnet greatmail.com 2500
  4. Hit enter
  5. 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.