Filters That Fight Back

[Matt Garretson]

In addition to the forged-address/innocent-bystander issue, I think
that generating bounces for spam is likely to "fight back" against
you more than it would against any spammers.  My guess is that, more
often than not, your bounce message will simply bounce right back
to you, since any emails addresses that may be grokked from the spam
will either be non-existant, or won't accept mail.  (And, as has been
mentioned here already, the addresses that do exist and do accept
mail will probably belong to innocent third parties.)

If you really want to generate some form of rejection, do it before
the first relay completes, so you can simply reject the message while
the connection is still active, and thus let the other relay host
decide where to send a bounce.  Of course, this would likely require
integrating bogofilter with your MTA in an atypical manner (e.g. a
sendmail milter).

-Matt