[Exim] pipe_transport_filter and looping

Hi ,ALL!
Help me, please.
i want to redirect all mail to other mailer through pipe.
i defined sistem filter like:

-------
if not first_delivery
then
finish
endif

pipe "/usr/lib/sendmail -f $h_from: $h_to:"
finish
--------

But i receved in log file string like : *** Too many "Received" headers
- suspected mail loop
Each time i received first_delivery mail, why ?
How to fix this ?

What's wrong ?


Konstantin Sapronov