Custom pipe script failure code

Hello, I have a quick question regarding the pipe function in Postfix and the use of PHP as a mail sorter/parser. I've looked around and see many people have used PHP as a quick and dirty solution for putting mail data into a database. I am taking all incoming mail, parsing out headers and putting the mail into a MySQL database. The problem I have is, if the script cannot connect to the database, the script fails. What I want is to have this message return back into the normal mail queue with a temporary failure or something so it can retry at a later time without disappearing into never never land. The reason for this, is if there is a connection failure, or the database stops for some reason, I don't want these messages to be lost due to a script failure. Here is my pipe command: spamfilter unix - n n - - pipe flags=DRq user=spamfilter argv=/scripts/spamfilter.sh -f ${sender} -- ${recipient} Here is my spamfilter.sh command: #!/bin/bash /usr/bin/spamc -f -u "$4" | /scripts/parsemessage.php "$4" exit $? So is there a way to exit(); with some sort of code to put that message back into the queue? I have read that I need to exit(75); but that does not work. If anyone could help, that would be more than fantastic. Thanks, Alan