The term 'EHLO' is not recognized as the name of a cmdlet, function, script file, or operable program

Question

I've installed and configured SMTP server on Windows Server 2012 R2 Standard. The installation and configuration was successful, to the best of my knowledge.

But I'm having issues with testing the SMTP server configuration by sending an email message using the SMTP server. I used telnet by running the following command:

telnet localhost 25

I get an error message, whenever I try to start communication with the server by running the following command:

EHLO server

As follows is the error message:

EHLO : The term 'EHLO' is not recognized as the name of a cmdlet, function, script file, or operable program. Check
the spelling of the name, or if a path was included, verify that the path is correct and try again.
At line:1 char:1
+ EHLO server
+ ~~~~
    + CategoryInfo          : ObjectNotFound: (EHLO:String) [], CommandNotFoundException
    + FullyQualifiedErrorId : CommandNotFoundException

Your help would be much appreciated. Thanks.