Telnet uses the Telnet protocol (part of the TCP/IP protocol suite) to connect to a remote computer over a network. You can execute telnet from the Command prompt (DOS prompt)

Syntax:

telnet [RemoteServer] [Port]

[RemoteServer]: specify the name of the server to which you want to connect. When you connecting to an email server you need to use the MX record value.

[Port]: enter the port that you want to use.

For Windows users:

  1. Go to Start > Run (or press Windows button+R).
  2. In the Run window type cmd and click OK to open Command prompt.
  3. Type in telnet [RemoteServer] [Port]. If you are trying to connect to Smarsh Hosted Services mail server, type in your MX record for the [RemoteServer]. Usually, port 25 is used for this type of connection. 
    telnet
    To terminate Telnet session use the "quit" command.

Note: by default, Windows do not have the Telnet client enabled. To install Telnet, follow these steps:

  1. Click the Start button, type in Control panel and click the Control Panel App.
  2. In the Control Panel, click Uninstall a Program under Programs section.
  3. Then click Turn Windows features on or off and after you click Continue on the security prompt, you should see a list of components.
  4. Scroll down to Telnet Client and check the box next to it. Click Ok to install the client.
     

For Mac users:

If you have OS X, you can use the built-in network tools.

  1. Click Go > Utilities.
  2. In the Utilities folder open Terminal.
  3. In Terminal, type: telnet [hostname] [port].