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.