arbitrarymail.sh

#!/bin/bash
# Easily test mail sending without anything but netcat.
# Instead of processing responses, it just slows down lines
# it sends and assumes it got a valid response.

FROM="$1"
TO="$2"

# Change these as appropriate.
EHLO="mail.example.com"
SERVER="example.com"
SUBJECT="Test Subject"

function delayit() {
IFS='\n'
while read i
do
echo "${i}"
sleep 1
done
}

function msg() {
delayit <<EOF
ehlo ${EHLO}
MAIL FROM: <${FROM}>
RCPT TO: <${TO}>
DATA
EOF
cat - <<EOF
From: <${FROM}>
To: <${TO}>
Subject: ${SUBJECT}
Dear User,

This is a test email.

End of message.
.
EOF
sleep 1
echo quit
}

msg | nc -v "${SERVER}" 25