Mail Processing - Bounce

I'm building a tool to process incoming mail. So far, I have a script that receives mail that is piped to it. I am able to process the mail without a problem. However, the script causes a bounce message containing the output of the script. Does anyone know how I can fix this? The script: http://www.janix.net/test/mail.phps The bounce message: This message was created automatically by mail delivery software. A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed: pipe to |/www/test/mail.php generated by ####@janix.net The following text was generated during the delivery attempt: ------ pipe to /www/test/mail.php generated by ####@janix.net ------