[exim] Rejecting attachment extensions on a per user basis

Hi!

I am trying to configure exim4+sa (from debian's exim4-daemon-heavy) to
reject messages based on the attachment extensions *on a per user
basis*.

I guess that the main work should be done on the acl_check_data section.
This section has, by now

deny message = .$found_extension files are not accepted here
demime = exe:eml:lnk:com:vbs:pif:scr

This is fine. But i would want to prevent just a couple of users from
receiving .zip files too. I can hardly find any documentation.

¿Is there any guru here willing to help?

Regards

--
Eduardo Diaz Comellas <ediaz@???>
Ultreia Comunicaciones S.L.