[Spambayes] Bouncing Spam

[T. Alexander Popiel]

In message:  <3DE4A5DD.9010904@startechgroup.co.uk>
             Matt Sergeant <msergeant@startechgroup.co.uk> writes:
>Steve Atkins said the following on 27/11/02 04:17:
>> The only way to safely bounce spam is to drop it with a permanent
>> (5xx) rejection at an appropriate point in the SMTP transaction at the
>> first point it enters your network (i.e. if your secondary MX accepts
>> it, don't reject the delivery to your primary).
>
>Another thing that came up discussing this on the SpamAssassin list is 
>that this only works on the mail server that is your MX server. If you 
>get mail through a third party (e.g. an ISP that might forward to your 
>SMTP server) then it doesn't work.

As an aside, I'll note that it's perfectly reasonable behaviour to
have a bounce response late in the forwarding chain (as in a primary MX
rejecting it when a secondary MX accepted it).  The problem is not with
a violation of SMTP, but in the fact that the spammers routinely ignore
foreign-generated bounce messages (since that would require them to run
an SMTP server of their own (and actually process data from it)) and
only pay attention to errors in outgoing conversations that their mail-
blasting tools have.

- Alex