North American Network Operators Group

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Re: Anti-spam System Idea

  • From: Andy Dills
  • Date: Sat Feb 14 14:05:47 2004

On Sat, 14 Feb 2004, Tim Thorpe wrote:

> I wanted to run this past you to see what you thought of it and get some
> feedback on pro's and cons of this type of system.
>  I have been thinking recently about the ever increasing amount of spam that
> is flooding the internet, clogging mail servers, and in general pissing us
> all off.
> I think it time to do something about it. very few systems are effective at
> blocking spam at the server level, and the ones that exist have a less then
> stellar reputation and are not very effective on top of that.

I used to agree with this, until I tried amavisd-new with spamassassin.

Yes, you have to throw a little hardware at it, but it really is an
effective solution. For my mail, it's more than 99% effective. The only
falsely tagged messages (never had a message reach the "bounce" threshold
as a false positive) are mailing list mails from people who are on

Because amavisd-new has support for querying mysql maps, it's trivial to
create multiple filtering policies, allowing users to select their own
through your online account management interface. Along with that is
per-recipient sender whitelists (and blacklists). And since amavisd-new
has support for most virus scanners (clamav is nice and free), it really
provides a complete solution.

Note, however, that amavisd-new works best with postfix (according to the
developer). Not sure how well it works with the others.

It was nice going back to getting around 1 spam per day in my
inbox...(over 200 are tagged or rejected every day).

This solution really antiquates the old paradigm of rejecting based purely
on status in an RBL.

I encourage everybody who runs a mailserver to read


Andy Dills
Xecunet, Inc.