[Exim] Preventing a bounce conditionally

I've just installed an exim with SpamAssassin box to act as a gatekeeper
for another system (which can't handle the anti-spam stuff).

My new box accepts mail for the domains handled by the original mailer,
scans for spam (adding headers and rewriting the subject header if it is
spam), then passes the mail directly to the original box. Once people
are satisfied I can probably start dropping the spam - but for now I
can't.

Works fine. Everybody happy.

However, as my gatekeeper box does not have access to the user data, I
can't check the recipient address is valid. Whereas this does get
checked on the destination box. So when I'm passing a mail along and
the recipient is invalid, my gatekeeper generates bounce.

Which is obviously what I want.

Except if the message has also been tagged as spam I don't see the point
in generating a bounce. The original sending domain is valid or my
gatekeeper would not have accepted the mail. So it's either fake, or
it's a red herring in the DNS which doesn't accept incomming
connections. Either way I'd just like exim to giveup (and to log the
fact).

After scratching my head for a few hours I don't seem to be able to
workout a solution.

Anyone any ideas?


(BTW: I'm using spamc in a router rather than exiscan-acl)

--
TTFN, FNORD

Peter McGarvey
Freelance FreeBSD Hacker
(will work for bandwidth)