cutting spam

Thursday, April 01, 2004, at 07:03AM

By Eric Richardson

On my server I've been running a SMTP server called qpsmtpd. It's cool because it's written in Perl and supports some good hooks for connecting in plugins. The other day, fed up with the amount of energy the server was putting into accepting and bouncing spam, I decided to see what was out there ease the situation. I ended up installing the denysoft_greylist plugin, which implements the greylisting concept found here. The basic idea is that messages are soft-failed the first time around, so that the sending server has to retry. If the server retries after a set grey period, the message is accepted, and the server is flagged white for the next couple weeks (so that it's imediately accepted). Basically what this does is attempt to prey on the fact that most spam solutions are doing a fire-and-forget, trying the message once without waiting to see what happens or follow appropriate RFC's for how to deliver.

The result? My daily spam has gone from about 450 messages/day to maybe 15, most of which are bounced over by speakeasy's mail server from my account there (and which I really could just filter into a blackhole if I wasn't lazy). I'm happy.