Huy's Notes
Verify email with telnet

Verify email with telnet

The method described below will check if an email address is real or not, without sending any email to that address.

First, connect to the mail server at port 25 (SMTP)

telnet smtp.google.com 25

Identify yourself as example.com with HELO command

HELO example.com

Identify your email address as [email protected] with MAIL FROM command

MAIL FROM: <[email protected]>

Now use the RCPT TO command to check if the email is exists or not

RCPT TO: <[email protected]>

Depends on the response you'll know if it's real or not.


In reality, email verifying is not as simple as described above, there are a lot of other things to check like, check for the existence of the server, some server doesn't support RCPT TO command, there are many different responses, in some case, we might need to check if the email is the disposable one or not,...

See the check-if-email-exists project from ReacherHQ below for more details.


Read more:

Referred in


If you think this note resonated, be it positive or negative, please feel free to send me an email and we can talk.