Re: spam control

[Tzafrir Cohen <tzafrir@cohens.org.il>]

On Sat, Feb 28, 2009 at 09:29:10AM +0530, Girish Kulkarni wrote:

> How is your experience with the spam control tools already available
> (SpamAssassin, SpanBouncer, Bogofilter)?  Which one is the most
> favoured?  Is Gmail indeed the best option for controlling spam?

At work I'm forced to use gmail. As I don't like its interface
(including the strange imap semantics) I just pull everything via pop3
to my own server. At "home" I just use postifx/dovecot-imap. I use
spamassassin as the spam filter.

With most lists I filter in my fetchmailrc before calling to
spamassassin, as those lists rarely have spam. Debian lists seem to have
more spam than others[1] and thus I do filter them.

Even with spamc (the small client that connects to a running
spamassassin daemon) I can still get heavy load from several
simultanious assassinations. Hence I have:

  # The lock file ensures that only 1 spamassassin invocation happens
  # at 1 time, to keep the load down.
  #
  :0fw
  * < 256000
  | /usr/bin/spamc

To make it simpler to search for mistakes, I filter the worst offenders
to a separate folder:

  :0
  * ^X-Spam-Level: \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*
  .spam-bad/

  :0
  * ^X-Spam-Status: Yes
  .spam-maybe/

I use the 'autolearn' feature of SA (which is enabled by default). This
saves me most retraining, but I still need to correct errors.
If a spam does get through I move it to the folder 'spam' . In my
crontab I have a daily job that learns new spam from there.

  $ crontab -l
  # m h  dom mon dow   command
  10  4  *   *   *     /home/tzafrir/bin/spam_learn

  $ cat /home/tzafrir/bin/spam_learn
  #!/bin/sh

  DIR=$HOME/Maildir/.spam
  DIR_NEW=$DIR/new
  DIR_CUR=$DIR/cur

  sa-learn --spam $DIR_NEW $DIR_CUR


[1] This is due to the policy of allowing anyone to post. I must say
that I'm surprised at just how little spam gets through - Admins of the
liszt-server are doing a great job. And I fully appreciate this policy 
and occasionally post to Debian lists I'm not subscribed to)

-- 
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