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

sleep 1
echo HELO
sleep 1
echo 'MAIL FROM:<[email protected]>'
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" <[email protected]>
To: <[email protected]>
Subject: Something good...
MIME-Version: 1.0
Content-Type: text/plain;
Content-Transfer-Encoding: 7bit

LOL - Lots Of Love.

Then you call it and pipe it to nc with the smtp server on port 25:
./ [email protected] | nc 25

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