Milter-greylist

Michael Fromme schreef:
> we have some Perl script for this, showing that for the last
> month 68 % of all delivered external mail came through immediately,
> 75% after 15 minutes, and almost 90% by 2 hours

What I do is, verify the if IP address of sending machine corresponds 
with the MX IP address for the sender domain. I match those with a 
generous /24 subnetmask. E.g. mail sent from a valid mailserver is 
accepted without delay, otherwise I greylist.

Furthermore I also accept email where the Sender IP address directly 
matches the domainname in question. This is useful where some mail 
forms/bots on webservers send email directly with regards to website 
registrations.

With this approach I get just 1 call a month regarding our greylisting 
effort. This is a company with about ~150 employees, 7 domains, 
including some very public email addresses.

Cheers,

Seth