Milter-greylist

Dan,

> Yes, because large ISP has potential ENORMOUS list of ip+address+datetime 
> pairs. Imagine ISP with 50k+ users and tens of millions of hosts sending 
> it mail. (eg typical large university)

I have found it easy enough to keep the size of the database down by 
using a local whitelist of companies and mailservers that I trust. That 
way the entries never get listed in the database.

Personally I have found greylisting to be the most effective against 
dynamic hosts, it stops spam and virus spew.

However greylisting is not effective against ISPs or organisations with 
large mail server clusters.

You also might like to try the LAZYAW option, and -L 24 to keep the DB 
size down.

Anyone wishing to share a local whitelist please let me know, mine is 
mainly AU organisations and ISPs :-)

Regards,

Joseph