[exim] lookups in exim filters?

In light of the system filter, I would like to do lookups. E.g.

# Exim Filter

if foranyaddress $recipients (${lookup{$thisaddress}lsearch{/opt/exim/spamtrap})
then 
        save /var/mail/spamtrap
endif

... where /opt/exim/spamtrap is a set of false addresses inserted into our webpage.


Or would this be better done in an acl.
--
Sherwood Botsford
St. John's School of Alberta