Milter-greylist

Gary Aitken <greylist@...> wrote:

> This seems not particularly useful to me.  We get very little mail
> addressed to non-existent users. 

Lucky you.

> Furthermore, any mail addressed to
> non-existent users is already rejected by sendmail anyway,
> so I don't see the need for greylisting to deal with it.
> A complete reject is preferable to greylisting in this case.
> Is there something here I don't understand?

The idea is to keep track of systems reputations: a system that sends
many broken mails will be delayer for longer, possible raising the delay
enough so that the mail is never accepted.

The idea has some benefits to temporatily (on a day basis) refuse
messages from real MTA used as relays by spammers, but there are issues
that need to be addressed:

- how milter-greylist could know about invalid addresses?
- couldn't we have more ham reject than spam reject with that method?

The first problem can be addressed by honeypots, but in fact it can be
fully jandled outside of milter-greylist. See ftp://ftp.espci.fr/pub/dst
for a real-time distributed spamtrap network. It works with any MTA.

I never pushed it very hard because for now greylisting is enough. DST
will also cause me to blacklist ISP MTA used as relays by spammers. If
someone has an idea on how to handle that...

-- 
Emmanuel Dreyfus
Il y a 10 sortes de personnes dans le monde: ceux qui comprennent 
le binaire et ceux qui ne le comprennent pas.
manu@...