Re: [Asrg] Re: SPF abused by spammers

[Seth Breidbart <sethb at panix.com>]

It's an arms race, as always.  No single weapon wins.

SPF helps.  Here's how, in the presence of domain-burning
SPF-publishing spammers:

1. Greylisting:  Email from a new domain that passes SPF is greylisted
   for 30 minutes.

2. Spamtraps: Email that hits a spamtrap, and which passes SPF, causes
   the domain to be blacklisted.  This will typically take well under
   30 minutes for a serious spam run.

3. When the greylisting expires, the domain is blacklisted.

The spammer has an incentive to push out crap quickly, in order to get
a lot past the non-greylisting receivers before he hits the blacklist;
he also has an incentive to push crap out slowly, hoping to get some
through to the greylisting sites before he hits the blacklists.

Seth

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