North American Network Operators Group
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Re: Large Mail Provider Throttling

  • From: Suresh Ramasubramanian
  • Date: Thu Jan 22 22:07:22 2004 
Aaron Thomas  [1/23/2004 8:28 AM] :


Sender Permitted From (http://spf.pobox.com/) attempts to eliminate Joe
Dropping from domain.com by doing a look up on a TXT record similar to

[...]

As this project is fairly new, there aren't many large domains making use of
it, and the tools available aren't mature enough for some email
What I described in my earlier email (helo filtering) is aimed at the same result. Only, it has to be done on a case by case basis. And it does allow road warriors.

The second way (slightly more radical, prone to a little more collateral damage, but does stop a LOT of spam) - stop accepting mail from commonly forged freemail domains if the mail originates from an IP with either

* no rDNS
* generic (dialup / cable / dsl) pattern rDNS

--
srs (postmaster|suresh)@outblaze.com // gpg : EDEDEFB9
manager, outblaze.com security and antispam operations