Scan all incomming/outgoing

 Hi there, Ive been attempting to incorporate rules in my sendmail.cf to
scan all messages, incoming or outgoing through a perl script Ive written. 
The machine in question, running sendmail, acts as a primary mail relay to
& from our orginization. Im not a ruleset wizzard, as well, Im sure people
have done this before. Here are the goals: 

All incomming/outgoing mail is fired off to the perl script
S0 (should i do this here?)     
R$*(_at_)$*     $1(_at_)$2(_dot_)filter
R$*(_at_)$*(_dot_)filter        $#procmail $@/usr/local/etc/procmailrc 
$:$1(_at_)$2
R$*(_at_)$*(_dot_)filter        $:$1(_at_)$2

 My problem is when the perl script re submits the message it will loop
infinate, I guess im just not bright enuff to work out the ruleset to keep
this from happening :) any sudgestions are appreciated.