Tag Archives: procmail

My Antispam Measures

I get a fair share of spam. I have something like 10 working private email addresses, I'm listed as recipient in numerous email aliases and they all end up in the same physical mailbox where I read them. I've also had my existing emails for many years and I've shown and used them publicly on the internet all the time. I'm a major spam email target now. A good day I get just 2000 spams, but bad days I've been well over 13000 spam emails.A can with spam

My biggest friends in this combat are: spamassassin and procmail.

I'll describe how I have things setup, not as much as to inspire others but more to be able to get feedback from you on how I can or perhaps should improve my setup to get an even better email life.

  • I consider all mails with spam points >= 3 to be spam. I've also tweaked my spamassassin user_prefs to be harsher on (pure) HTML mail and a few other rules, and I've added a couple of my own rules to catch spams that previously did slip through a little too easy.
  • First, I filter out mail from trusted mailing lists that have their own antispam measures.
  • I catch what appears to be bounces (I have a huge regex) and if it looks like a bounce to an address I don't send email from I nuke it immediately (and those could be a true bounce are saved in a dedicated mbox)
  • I have a white-list system that marks all incoming mails from previously marked friends as coming from a friend.
  • Mails from non-friends are passed through spamassassin. Those with spam points higher than N are put in the 'hispam' folder - of course with the intention that these are very very very unlikely to every have any false positives and can almost surely be deleted without check. N is currently 10 but I ponder on lowering it somewhat. Spams with less points than N are put in the 'spam' folder, and I need to check that before I kill it because it happens that I get occasional false positives that end up there.
  • So, mails that aren't from friends (or from a trusted mailing list) and aren't marked as spam are then stored in the 'suspicious' mailbox
  • Mails from friends or from trusted lists go directly into my mailbox, or into a dedicated mailbox (for lists with somewhat high traffic volumes).
  • Oh, a little additional detail: I "mark" my own outgoing mails with an additional custom header with no point whatsoever but to be able to detect when someone/something sends me mail using my own address...

My weakest point in all this right now is the fact that I don't spam-check white-listed mails at all, so spams that are sent to me using my friends' email addresses go through and annoy me.

BTW, I did use bogofilter in the past and for a while I actually ran both in parallel (both trained with rougly the same spam/ham boxes for the Bayes stuff) but quite heavily testing I performed at that time (a few years ago) showed that spamassissin caught a lot more spams than bogofilter, while bogofilter only caught a few extra so I dropped it then.