smtp_email_verifier

SMTP Email Verifier (python)

SMTP Email Verifier makes correct SMTP conversation to verify email address or list of addresses

This tool could be slow - it's not working parallel.

verifier prints successfully verified email addresses to stdout, and failed addresses (and reason) to stderr.

Why yet another mail list verifier?

Because many other verifiers are working incorrectly, e.g. They use incorrect HELO host, do not issue MAIL FROM command before RCPT TO and on some mailserver this makes incorrect result (e.g. RCPT TO fails because of missed MAIL FROM, but not because something wrong with recipient).

SMTP Email verifier:

1. Connects to main MX for domain (with lowest MX priority)
2. Makes correct (configurable) SMTP conversation with HELO / MAIL FROM / RCPT TO
3. For each failed email prints (easy to parse with cut -f 1 -d )

Install

pipx install smtp-email-verifier

Usage

Verify one email address

$ email_verifier [e-mail]
[e-mail]

$ email_verifier [e-mail] > /dev/null 
[e-mail]: RCPT TO error: 550 b"5.1.1 The email account that you tried to reach does not exist. Please try\n5.1.1 double-checking the recipient's email address for typos or\n5.1.1 unnecessary spaces. For more information, go to\n5.1.1  https://support.google.com/mail/?p=NoSuchUser 41be03b00d2f7-78e43192d3esi9685918a12.435 - gsmtp"

Optionally provide options --helo HOSTNAME and --from ADDRESS.

Verify list

# See verification status for each email address
$ email_verifier -f /tmp/test.txt 
[e-mail]: DNS error for example.com
[e-mail]: DNS error for example.com
[e-mail]

# Get only verified emails
$ email_verifier -f /tmp/test.txt 2> /dev/null 
[e-mail]

# Or with redirections and custom HELO and MAIL FROM address
$ email_verifier -f /tmp/test.txt --helo localhost --from [e-mail] > /tmp/test-ok.txt 2> /tmp/test-fail.txt
# now get all failed addresses:
$cut -f 1 -d: < /tmp/test-fail.txt

Verbose

If you want to see how exactly verification happens for email address, use -v / --verbose:

$ email_verifier -v [e-mail] --helo localhost --from [e-mail]
# Verifying [e-mail]
connect: to ('gmail-smtp-in.l.google.com.', 25) None
reply: b'220 mx.google.com ESMTP 38308e7fff4ca-2eee192b083si25595201fa.355 - gsmtp\r\n'
reply: retcode (220); Msg: b'mx.google.com ESMTP 38308e7fff4ca-2eee192b083si25595201fa.355 - gsmtp'
connect: b'mx.google.com ESMTP 38308e7fff4ca-2eee192b083si25595201fa.355 - gsmtp'
send: 'helo localhost\r\n'
reply: b'250 mx.google.com at your service\r\n'
reply: retcode (250); Msg: b'mx.google.com at your service'
send: 'mail FROM:<[e-mail]>\r\n'
reply: b'250 2.1.0 OK 38308e7fff4ca-2eee192b083si25595201fa.355 - gsmtp\r\n'
reply: retcode (250); Msg: b'2.1.0 OK 38308e7fff4ca-2eee192b083si25595201fa.355 - gsmtp'
send: 'rcpt TO:<[e-mail]>\r\n'
reply: b'250 2.1.5 OK 38308e7fff4ca-2eee192b083si25595201fa.355 - gsmtp\r\n'
reply: retcode (250); Msg: b'2.1.5 OK 38308e7fff4ca-2eee192b083si25595201fa.355 - gsmtp'
send: 'quit\r\n'
reply: b'221 2.0.0 closing connection 38308e7fff4ca-2eee192b083si25595201fa.355 - gsmtp\r\n'
reply: retcode (221); Msg: b'2.0.0 closing connection 38308e7fff4ca-2eee192b083si25595201fa.355 - gsmtp'

[e-mail]