[Exim] Command Execution

I have set up a .filter file for a regular user.
I want it to run a perl script on every incoming message to this user.

I have in ~user/.forward

# Exim Filter
command = /usr/bin/test.pl

This does not work, I get
unknown filtering command "command" near line 2 of filter

I took this from the Exim book pg 225.
I get the same error if I try to use "use_shell" in my
filter.

--
Joseph Kezar