[exim] not generating undeliverable mail messages

Hi,

I run the departmental email system for a department at the university
of warwick, our setup whilst it may seem strange comes from the need to
maintain legacy email addresses.

Our setup is as follows.

We have a main departmental email server, protein, which runs exim on
linux, this is the primary mx server for all the other email servers
withing the bio.warwick.ac.uk domain, to which it forwards mail as needed.

The other mail servers are :-

Mercury running on a novell fileserver.
Exim running on several group mailservers on linux (matterhorn, globin).

Protein also has an alias system running on it (mysql/php driven), to
allow us to re-direct, our users email elsewhere as needed.

It should be noted that all user@??? email goes to
protein, if it can't be delivered there, protein will attempt to deliver
it to the novell system, obviously it has no way of knowing if the user
on the novell system is valid, until delivery is attempted.

We are having problems with spam email bounces generated from
undeliverable addresses on the servers that we route for, the problem
being that protein has no way of knowing if users at the system it
forwards for exist, so has to accept all mail for them and attempt
delivery, which of course if it fails generates a bounce message, often
containing spam. What I would prefferably like to do is just drop these
on the floor and generate no bounce back.

Does anyone have any idea how I would go about doing this, or have a
better sugestion as to what would be a better course of action.

Cheers,

Phill.

--
Phill Harvey-Smith, Computer Technician,
Department of Biological Sciences, Warwick University.
Email: phill@???, Phone: 024 7652 8385.
"The Days' as dark as the night is long" -- U2, Ultraviolet.