[Exim] .forward filtering, logwrite and cPanel

The hosting company that I'm using is running exim 3.36 and
cPanel 6.4.0. Whenever I try to do a logwrite from a .forward filter
file I get the following error:
D=userforward defer (-11): error in filter file: logwrite command not
permitted when filter not running as user
I suspect that the problem is caused by the way that cPanel has
configured exim. Does anyone have any suggestions?