Slowing down smtpserver (was: Re: A potential way to cut down on spam.)

[acli@ada.dhs.org]

In article <1075920710.31943.55.camel@ariel.sovam.com>,
Eugene Crosser <crosser@rol.ru> wrote:

>We use different scoring model, and different way of throttling
>(make smtp server appear very slow rather than reject message),
>but otherwize, I too think that "dynamic reactive" approach is
>the most useful one.

Before I switched to Eugene's zmscanner, my content filter
would often spend too much time analysing messages (not because
it's being thorough, rather the opposite: because my code is
poorly written and Perl is too slow for that box). I felt that
making the smtp server appear very slow *might* actually cause a
problem.

Some servers seem to have a very low tolerance of how "slow"
they can handle; any slower than that and they would assume your
server is down and they abort and retry later.

Does anyone have similar experiences? What would be a good
absolutely-maximum delay (e.g., for "tarpit")?

-- 
Ambrose LI Cheuk-Wing  <a.c.li@ieee.org>

http://ada.dhs.org/~acli/
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