[exim] file lookups in sysgtem filters

I use file look-up in the main EXIM configuration for aliases etc but
would like to look up a file in a System Filter e.g. if the sender is on
a list then ...



So far I have failed to get a filter to work. If anyone has an example
the please could they share it with me or if it is not possible then I
will stop trying and look at writing a Perl program and pipe the message
to it.



John Linn