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RE: [Asrg] Taxonomy of anti-spam systems

2003-03-10 13:26:20


On Mon, 10 Mar 2003, Vernon Schryver wrote:


Teergrubbing sounds silly to people who know that some spamware uses
illegal SMTP command pipelining.  Some spammers send send the entire
client SMTP transaction including the ending TCP FIN before the STMP
server has finished doing the reverse DNS lookup to decide whether to
post its banner.  Whether the STMP server delays 10 ms or 10 hours is
of no concern to them.  


Yes, but some spammers do not control the relevant MTA, as for example if
it is an open relay. Teergrubing must have very strong incentive effects
on open relays if it becomes reasonably widespread. And this incentive
applies even if the relay has no legitimate mail to transfer to the
victim.

Daniel Feenberg



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