[Gllug] Whitelist-only spam filtering

[Stig Brautaset]

On Sep 12 2002, Simon was overheard saying:
> 1) I'm not talking about lettings some shadowy third party filter my
>    mail.  I'll do that and maintain the filters myself.  I'm convinced
>    that whitelists are the only way forward and, if implemented
>    correctly, will not result in lost mail.
> 2) Spamassassin isn't good enough.  I get far to many false-positives
>    and it lets through stacks of spam -- notably recently have been
>    the classic Nigerian scams.
> 
> However, the Spamassassin approach is good.  I like the idea of
> scoring and that would be useful for the stuff that isn't in the
> whitelists or is in a provisional whitelist.

I have a procmail-based conditional scoring spamfilter thingie. It 
contains a white/blacklisting functionality (albeit slightly different 
in nature than you sketched out, it's trivial to change) that can be 
updated by sending emails from/to a specific address. Additionally, 
if the filter doesn't detect spam correctly, I can just forward the spam
to myself, and the sender will be added to the blacklist.

I wrote this filter when I was on the debian-user mailing list; the spam
on that list is not half as irritating as the 20-30 posts coming as 
follow-ups to this thread. My filter implements a feature where it 
caches the Message-Id field of messages that are detected as spam (or
told so by me as mentioned above) and files all followups to these 
messages as spam also. There is also a functionality to plonk followups
to a message without putting the sender of the message on the blacklist
(iirc). This filter is kinda work-in-progress that never got finished 
off. I use it on my system though, and it works quite well.

The procmail file can be found at
        http://brautaset.org/config/procmailrc 
It obviously need some tweaking before it is usefull to anybody else, 
but it should be trivial to do. I have littered the source with comments
(probably a bit too much actually) so it shouldn't be hard to 
understand.




Stig
-- 
brautaset.org




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