[Spambayes] Bouncing Spam

[Steve Atkins]

On Tue, Nov 26, 2002 at 09:22:03PM -0600, Tim Stone - Four Stones Expressions wrote:

> This is a bit off topic, but perhaps someone knows... Is it possible to return 
> a mail in such a manner that it appears to the sender to have bounced?  It'd 
> be real nice to have a 'bounce' option for spam, so that the senders *might* 
> take the address off their list, if they think it's a dead address...

Yes, there are programs that'll do this by sending mail that looks
like a bounce message. They're pretty worthless because you have no
idea who the original sender was. Typically the faked bounce ends up
at an innocent third-party (if the faked from address exists) or a
doublebounce/postmaster mailbox (if it doesn't). Don't do this unless
you deeply understand what you're doing and why.

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). Even then you need to
read RFC 2821 very carefully. A lot of people throw non-defined errors
or throw them at the wrong point in the transaction, which can make
things worse rather than better. Doing this with the MTAs support is
the only easy way to do it.

Cheers,
  Steve