On Tue, 2003-12-16 at 10:26, Leonard Spell wrote:
> Is it better to start with existing blacklists instead 
> of creating my own?

I'm no expert but here is what I learned lately.

You should use existing blacklists for the general cases and your own to
further restrict the holes.

I think those 2 lists are essential:
cbl.abuseat.org
sbl.spamhaus.org 

They should cut the incoming SPAM by at least 50% and they generate
almost no false positive (or is it false negative?). In fact, absolutly
none for me.

Sprinkle a couple of well maintained lists:
relays.visi.com
dialups.visi.com
opm.blitzed.org
dul.dnsbl.sorbs.net
list.dsbl.org

Add to that as many country BL as you are confortable with. Those are a
must for me:

cn-kr.blackholes.us
russia.blackholes.us
singapore.blackholes.us
malaysia.blackholes.us
nigeria.blackholes.us
brazil.blackholes.us
taiwan.blackholes.us
turkey.blackholes.us
thailand.blackholes.us

Beware that the more lists you use the longer it takes the server to
accept a valid email because it has to go through every BL.

The listing order of the BLs has some importance. You want the most
effective at the top to minimize traffic. 

I add to my own BL any IPs from the SPAM that I receive. Sometimes I
block a full /16 sometimes just one IP. It's your call.

Use these sites to test IPs against a whole bunch of lists:
http://www.dnsstuff.com/
http://www.moensted.dk/spam/
http://www.openrbl.org/

Use SPAMTRAPs, they are very useful.

You might want to whitelist (Client Hosts) servers that are important to
your clients like the big local ISPs. 

Go slowly, watch your logs and notify your users that they might receive
complaints and advise them on how to deal with them. They will probably
thank you profusely once they see the results of your filtering. Mine
did.

To see hardcore anti-spammer at work, hang out in the NANAE newsgroup:
news.admin.net-abuse.email. You might learn a thing or two from them.

If/when you feel like doing more, install rbldnsd, a small daemon for
DNSBLs (http://www.corpit.ru/mjt/rbldnsd.html) and consolidate your
lists. It should cut on the traffic and the time to accept a valid
email. 

That's all I have to say.

May the anti-spam gods be with you.

Clem.


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