[PLUG] spam and white lists

Aaron Burt aaron at speakeasy.org
Fri Oct 3 20:14:01 UTC 2003


On Fri, 3 Oct 2003, Ed Sawicki wrote:
> On Fri, 2003-10-03 at 19:03, Aaron Burt wrote:
> > There are ways to classify (and filter) spam that are about as effective
> > as simple whietlists, but are much more flexible and involve much less
> > fiddling.  And keep in mind that the From: address is generally faked,
> > often with domain names and addresses that belong to legitimate users.
>
> We're talking about a large volume of mail. One goal is to
> turn away the spammers before they consume our bandwidth.
> Techniques that require us to receive the message before we
> decide that they're spam are not acceptable.

I understand.  There are several techniques that work well at that stage.
I'd recommend you look a little further into modern spam-fighting tools
and techniques (especially RBLs) before you invest too much effort.

One bandwidth-saving technique that I'm told works surprisingly well is to
give a temporary (4xx) error to unknown senders.  Spammers rarely retry
errors, so if the sender retries, it's probably OK and can be whitelisted.
(And have its mail subjected to further classification.)

The important bit here is to do something effective without incurring
excessive costs in programming or maintenance time.


The spammers don't deserve it,
  Aaron





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