[Exim] message filter

hi
i want exim to run a filter based on inbound email addresses, and pipe =
straight to a program e.g. to insert
content into a database and then pick up the same content.

following is my filter

if
    $header_to: contains "user@???"
 then
    pipe /mail/var/temp/mailbox
    finish
endif

--------------------
transport config
--------------------
address_pipe:
driver = pipe
user = exim
group = exim
return_output

but i think something is wrong some where here is log=20

2001-10-24 18:24:18 15wM8R-0003J3-00 = = |/mail/var/temp/mailbox = <message
filter> transporting defer
(-1): No transport specified for local delivery from system filter - =
check message_filter_pipe_transport

can somebody help me out and let me know where i'm wrong
thx
Madan