Jem Berkes wrote:
This is the problem encountered by many spam filters, as to be most
effective they really need to be _involved_ in the SMTP transaction and not
just stage 2, after receipt happens. Think greylisting as an example.
You read this?
http://www.acme.com/mail_filtering/
One thing that's critical isn't just having access to information
from early stages of mail processing, but being able to intervene at
early stages in the processing so to avoid the CPU and bandwidth waste
at advanced stages. This particularly matters during a computer virus
outbreak: I remember hitting on many of Jeff's solutions when a mail
server I managed was getting hammered by an incredible volume of
viruses, and I wrote scripts that picked up bad addresses from the
virus filter output and put them into the software firewall.
