[9fans] need help with improving my spam filtering

[Robert Raschke <rrplan9@tombob.com>]

Hi,

I have set up my Plan 9 box to receive email for myself.  It's a very
simple setup with no relaying, just for my own little maildrop.

This year the spam started to arrive in slightly more annoying
quantities, and a few months ago I managed to set up the bayes
filtering for my email.  This worked for a while, but now I am getting
more and more spam getting through (mostly because of the anti-bayes
mechanism of hiding the spam in a picture and sending it together with
random but apparently OK text).

So, I'd like to expand my spam stopping capabilities.  I have read
smtpd(6), ratfs(4), and scanmail(8) but find myself slightly at sea on
how to combine these to allow me to filter out some of the more
obvious spam.

If I understand correctly, I can start ratfs(4) and since it'll read
the default /mail/lib/blocked file my smtpd(6) will then block some
emails.  I can also replace qer(8) with scanmail(8) in my
/mail/lib/qmail and therefore block out even more emails.

The thing I don't yet fully grasp is how I manage the resulting
holding queues and log files and how I properly administer the
/mail/lib/blocked and /mail/lib/patterns files.

Can anyone point me in the right direction for learning more on how to
use ratfs(4) and scanmail(8) for effective spam filtering?

Robby

PS I guess an alternative approach would be for me to use fresh email
   addresses for mailing lists every so often.  But that feels
   shortsighted somehow.