SMTP authentication through TELNET

It's common that we use TELNET to port 25 of Mail server to check the connectivity and to ensure the Mail flow.

It's also possible to perform SMTP authentication in TELNET session

$ telnet yourmailserver 25
type “HELO”, hit Enter.
AUTH LOGIN

Now you have to enter your email ID and then your password encoded in BASE64.
For converting your email and password to Base64 use the conversion tools at WebPan or Ostermiller

Reference
WebPan.com
KongTechnology