[cobalt-users] Spam blocking

["Michele Neylon :: Blacknight Solutions" <michele@xxxxxxxxxxxxxxxxxxxxxxx>]

Reading over the last few days threads regarding spam blocking I've noticed
references to a large number of RBLs and a number of implementations of
same. It's nice to see that people want to block spam, but you need to be
VERY careful how you do this.

You may reduce your spam by 75% if you add in three or four RBLs at the MTA
level, but you are also going to block a lot of legitamate email in the
process if you are blindly grabbing tips of mailing lists.

I do not mean to be facetious about this, but if you are handling email for
a large number of users (ie not just you and your personal friends) you
could be placing yourself in a very precarious position.

Each RBL follows its own set of criteria. Some are very extreme (dynamic IP
blocks for example), while others may be blocking entire subnets based on
the netblock owner (or its predecessor).

If you are handling mail for third parties, as would be the case of hosting
companies etc., you may must not forget that you are as likely to be held
liable for the mail not delivered as the mail that is.

So do not blindly add RBLs to your servers unless you know what you are
doing.

Mr. Michele Neylon
Blacknight Internet Solutions Ltd
http://www.blacknightsolutions.ie/
http://www.search.ie/
Tel. + 353 (0)59 9137101