[Greylist-users] Greylisting with automatic IP address based whitelist

[Akihiro KAYAMA]

Hi all.

I have a fundamental question About Greylisting. This is not explained
in Greylisting whitepaper. I want to know any URLs if already
discussed.

My question is the reason why Greylisting does not use automatic IP
address based whitelist.

When a particular site has been successfully probed by triplet, it is
reasonable to consider the site to be driven by legitimate MTA. So if
the site deliver subsequent mails with different sender/recipient, as
long as IP address is the same, next probe should be the same result.
In this point, Greylisting with IP address based whitelist will
accomplish the same result, and significantly reduce delayed mails.

ISP's dynamic IP addresses is not a problem because there is few
servers on such addresses, clash with open proxy host is still rare.

Anyway, I have modified my greylisting script to do so and happily
enjoy greylisting power without special care about Ezmlm. I can't see
any evidence that same IP address host occasionally runs both
legitimate MTA and open proxy. 

Any comments will be appreciated. 
Thanks.

-- kayama