Spam bounce message

[Matt]

If the SMTP server the spammer connected to accepted the message it was
already marked quite likely as valid unless they used an open relay.
Usually the return address on a SPAM does not work anyway though.  Also,
just in case of a false hit you would want an explanation to a legitimate
sender.

Matt

> I've been playing with this in 4.0 and was wondering... Wouldn't it
> better for MS to bounce back the message in such a way that it appears
> to be a Mailer-Daemon rejection message?  Basically making it appear to
> have come from the MTA?  I wouldn't think spammers are going to look
> that closely at the header and see that it's not a real bounce.  If the
> bounce message appears to be a rejection then "maybe" and I do mean
> maybe, the address would get removed from their list.