[lug] Stopping the New Generation of Spam

[Daniel Webb]

On Mon, Dec 04, 2006 at 04:38:11PM -0700, Daniel Webb wrote:

> But assuming the SMTP server isn't totally broken, the sender's mail server
> will send them a bounce message letting the sender know that the message
> didn't go through, right?  The ones that scare me are the "silent" ones where
> the sender sends the email, SpamAssasin tags it spam and I delete it without
> looking at it.  The sender has no way to know that their message was deleted
> as spam.  With greylisting, they should get a bounce so that they can contact
> you another way.  Same if you move all spam filtering to SMTP-time: the sender
> always knows if their message was not delivered.  I like that property a lot.

[replying to myself again]

But on the negative side, I can imagine that any kind of trained filter can
not be used at SMTP-time because the spammers will have a nice fast feedback
loop to poison the filters or avoid them.  I think you could only use the
content-neutral techniques at SMTP-time, like DNS blacklists, HELO checks, and
greylisting.