bash and telnet to test an email
Try doing this :
[[ $4 ]] || {
printf "Usage\n\t$0 <domain> <email> <from_email> <rcpt_email>\n"
exit 1
}
{
sleep 1
echo "helo $2"
sleep 0.5
echo "mail from:<$3>"
sleep 0.5
echo "rcpt to:<$4>"
echo
} | telnet $1 25 |
grep -q "Unknown user" &&
echo "Invalid email" ||
echo "Valid email"
Usage :
./script.sh domain email from_email rcpt_email