milter-before is a small Perl milter script to prevent spam back-scatter.
Few years ago (200?) i was looking for a milter plugin to prevent our front smtp relay to accept mail for invalid user adresses on internal servers. Mails are always acceped, but when trying to deliver them to the internal smtp servers, they are refused, so we try to send them back to their senders which are a bad or faked addresses.
This problem is known as "spam back scatter". It provoque undesirable bounces. The only implementation of such mechanism where non free. So i wait...
In Octobre 2007, i started a free perl script to do the job. Using some mimedefang code, MLDBM and of course, Sendmail::Milter.
This beta version runs smoothly for several days whithout problems on our front smtp server. Its jobs is reduced because we run milter-greylist first.
- domain and subdomain match (one level only)
- persistent and tunable cache for good, bad, tempfailures
- munin ready
- perl customizable !