Today I turned on a filter on my incoming SMTP connections. I use qmail, so I used an old program that I wrote called qmfilt. (You can get it over at sourceforge).
I already got rid of my old email addresses with friends. However, if email gets sent to one of those old addresses, it still gets into my mail system, queues, try’s to send a bounce, which then goes to some bogus address. This then ‘double bounces’ and ends up in my ‘postmaster’ queue which I get in my inbox…. Joy.
So, I turned on qmfilt and hand coded a more restrictive pattern matcher on the envelope. If an email matches that filter, I cause a ‘hard bounce’… or ‘Sorry, no thanks, and don’t try again’ right at the end of the SMTP transaction. So far it has been working like a charm. I’ve blocked 1574 spam emails so far and they didn’t even get a chance to hit my disk. Much better.