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Date:      Thu, 21 Sep 2006 12:20:26 +0200 (CEST)
From:      Oliver Fromme <olli@lurza.secnetix.de>
To:        freebsd-stable@FreeBSD.ORG
Subject:   Re: Buckets of spam on list?
Message-ID:  <200609211020.k8LAKQLD013803@lurza.secnetix.de>
In-Reply-To: <200609201643.k8KGhWVI017986@fire.jhs.private>

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This is the wrong list to discuss such things.  Complaints
and notices about the spam filters at freebsd.org should go
to mailman@ instead of cluttering the discussion lists any
further, which is almost as bad as the spam itself.  Any
other discussion about spam should go to chat@.

Julian Stacey wrote:
 > Dave Horsfall wrote:
 > > Has FreeBSD's spam filter opened its legs again?  Along with MOBILE, ACPI, 
 > 
 > That phrase had me chuckle  :-) 
 > 
 > Other possibility is perhaps [...]

As far as I've heard, the spam filter on the incoming mail
server simply died for some reason.  It's now up again,
and spam level should be back to normal (i.e. almost zero).

 > (I run a hombrew anti spam here, (not dependent on imported RBL
 > lists or public tools, so immune to changes there),
 > but I think I'm seeing more spam too (apart from via @freebsd.org)).

I'm using sendmail's greet_pause feature + milter-greylist.
Those two measures block 80% of the spam, without any false
positives so far.  Additionally I use two conservatively
managed DNS blacklists (combined.njabl.org + list.dsbl.org;
see http://njabl.org + http://dsbl.org), plus a lightly
configured bogofilter (see ports) + a few custom mailfilter
rules (ports/mail/mailfilter).  Those cut the remaining 20%
that survive greylisting.  The result is almost zero spam.

Additionally, for usenet postings I use a small script that
generates a dynamic "From" address with a hash code, which
look like this:  "user+j5xtjy70rs16m1uz@domain.com".  The
hash code contains an encoded timestamp.  Any email sent to
such an address is passed through if the timestamp is
younger than two weeks.  If it's older, a mail is sent back
to the sender, asking him to reply to a new (fresh) address.
It's not a perfect solution, but works pretty well.  Most
personal replies to usenet postings are sent within 2 weeks
(many news servers don't even keep articles that long), so
there's no additional burden on legal senders at all, while
replies after 2 weeks are spam most of the time, as my
experience shows.

Best regards
   Oliver

-- 
Oliver Fromme,  secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing
Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd
Any opinions expressed in this message may be personal to the author
and may not necessarily reflect the opinions of secnetix in any way.

"I invented Ctrl-Alt-Delete, but Bill Gates made it famous."
        -- David Bradley, original IBM PC design team



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