nullmail

nullmail - A Null Router for SMTP

nullmail This is a very small, standalone binary that listens on a given port, speaks unencrypted SMTP, and dumps all the mail it receives to ... nowhere. You do get logs though!

Usage is simple:

$ nullmail
listening for inbound SMTP on :2525
>> received mail from from@foo for to@bar with subject: xyzzy

If you want a different port:

$ PORT=5587 nullmail
listening for inbound SMTP on :5587

If you want to save the logs:

$ nullmail | tee /var/log/nullmail.log

If you don't want the logs:

$ nullmail >/dev/null

etc.