Spoofing emails using netcat

There are a few legitimate times when you find a need to speak raw SMTP to send an email. Here’s some scripts I’ve used in the past to help with that task.
Let’s start with echo.sh:

#!/bin/sh
sleep 1
echo HELO nothax.nu
sleep 1
echo 'MAIL FROM:<me@mydomain.com>'
sleep 1
echo RCPT TO:$1
sleep 1
echo DATA
sleep 1
`cat letter.txt`
echo '.'

Inside letter.txt you’ll have:

From: "Test User" <test@user.com>
To: <whoever@domain.com>
Subject: Something good...
MIME-Version: 1.0
Content-Type: text/plain;
        charset="iso-8859-2"
Content-Transfer-Encoding: 7bit

LOL - Lots Of Love.

Then you call it and pipe it to nc with the smtp server on port 25:
./echo.sh johndoe@gmail.com | nc gmail-smtp-in.l.google.com 25

Goodluck! Feel free to leave a comment below with feedback and corrections. Also if you found this helpful and would like occasional updates of things happening in this arena subscribe to the newsletter. Thanks!

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