R Lists06 wrote:
A minute or two delay from grelisting matters that much????
Greylisting usually delay a mail for more than two minutes (when it delays, a
good implementation can excempt most mail from the delay after a while).
Even if the greylist implementation only enforces a one minute delay, most servers will
wait longer than that before retrying. 5-15 minutes seems to be pretty common
("seems" because I havent collected any statistics).
Just had a thought... Haven't thought it through or checked any stats for it,
so it may not be a good one.
The greylist code could be to do a reverse lookup and/or a DNS-list check on
the sending host before deciding wether it should be subjected to the greylist
or not. If it's in a dial-up-list, or the hostname fits a pattern for dial-up
and dyanamic addresses the host can be subjected to the greylist, and otherwise
it could be excempted from it.
Most spam that is stopped by a greylist is sent from zombies, so I wouldn't be
suprised if a greylist such as this could be pretty effective while minimizing
that impact on legit mail.
(When I get the time I'll do some stats on this, and if it seems like a good
idea I'll implement it in the code at
http://whatever.frukt.org/mimedefangfilter.text.shtml)
Regrads
/Jonas
--
Jonas Eckerman, FSDB & Fruktträdet
http://whatever.frukt.org/
http://www.fsdb.org/
http://www.frukt.org/
