* Tor Slettnes
> One thing I missed from your message was _at what point_ you want to
> invoke perl routines / have access to the entire message.
At any point I can do string expansion (${perl {...}}), but obviously
only after the entire message is received.
> Generally, if you want to run a routine for each recipient (e.g. in
> a user filter), you have already accepted the message. Your options
> for dealing with spam at this point are non-optimal (send a
> bounce/generate collateral spam, discard, freeze for review, filter
> into a separate folder..).
>
> A better way is to perform the filtering at SMTP time (i.e. in the
> Exim ACL), and reject (550) or greylist (451) suspected spam.
Well, obviously we disagree on what constitutes "optimal" spam
filtering techniques. By doing SMTP-time rejections you can pretty
much forget about using any kind of adaptive filtering method which
requires a feedback loop of some sort. Greylisting is a pain to deal
with when you run busy sites, I certainly hope it won't be much more
popular than it is today (at least not those which key off the sender
host plus the envelope recipient). There's a reason why Yahoo Groups,
for instance, have chosen to interpret 4xx as 5xx..
As for bounces being collateral spam these days, I agree. And by
doing SMTP-time rejections you create these as well, albeit indirectly.
Not to mention that everyone running relays will hate you for
filling their queue with undeliverable bounces.
> * Force one recipient per message by deferring subsequent
> recipients:
That's certainly a non-option. For my own personal low-traffic
domain, maybe, but not for the more trafficed sites I run. The users
would never accept the delays (and missing email from sites such as
Yahoo Groups) that limiting the envelope recipient tally to one will
impose.
Kind regards,
--
Tore Anderson
