John C Klensin wrote:
--On Thursday, November 26, 2009 9:20 PM +0100 Arnt Gulbrandsen
<arnt(_at_)gulbrandsen(_dot_)priv(_dot_)no> wrote:
Nate Leon writes:
I agree with Hector - the less detail the better when
communicating back to spammers.
Oh...?
People used to say that years ago. But now, we've had 15 years
experience with spammer. Mine is that spammers basically don't
bother to learn.
That's probably because they have plenty of easier methods to hit
their target. IOW, it is a symptom that mail admins don't deploy
countermeasures quite effectively.
Of course, if you know for certain that the sender is a spammer, then
returning "5yz FOAD" may be an appropriate response without any
additional information. But the reason for that is to avoid consuming
resources, not because the additional information would somehow be helpful.
SA provides a certainty measure, and a server may make different
decisions according to that score. Possible actions may include:
* set message header (SA default, Authentication-Results),
* set IMAP keywords (either Junk or NonJunk for TB users),
* deliver normally,
* deliver to a Junk folder,
* reject with various levels of detail,
* drop or quarantine, and possibly even
* create a record for a class of of messages (based on envelope
data) that the recipient can whitelist using a web form.
Is there an obvious decision matrix? In particular, would
reliability be better if a server rejects messages with higher spam
scores and delivers to a Junk folder for medium-to-hight, or the
other way around?