On Mon, 14 Feb 2005 10:51:33 -0600, Steve Drees <sdrees@???> wrote:
> I've laid out a recipe I use to provide opt-in spam filtering for our
> customers utilizing exim v3.x
>
> http://ironrangegeek.com/Exim3SpamFiltering
Thanks for publishing this. But unfortunately, it's a very good
example of how to implement accept-then-bounce spam filtering, which
is very bad practice indeed.
Since some very large percentage of spam arrives with forged sender
addresses, you either send notifications to innocent victims whose
addresses were forged (thus compounding those peoples' junk mail
problem), or at best, you clog your mailq up with undeliverable
notfications to the rest.
The tiny percentage of spam which arrives with a genuine, deliverable
sender address which actually belongs to the spammer... why do you
want to tell them anything at all?
You shouldn't do this. You certainly shouldn't encourage other people
to. Reject unwanted mail at SMTP time.
Peter
--
Peter Bowyer
Email: peter@???
Tel: +44 1296 768003
VoIP: sip:peter@???
