STDIN, email, php as cgi

Hi, In conjuntion with my ISP, I have figured out how to forward incoming emails to a certain address, or with a certain subject, etc, to trigger a php script, using php as a cgi module. I have been able to use this php script to send an auto-reply, but now I want to use the contents of the original email (to, from, other headers and message body) in the script (example, forward a message on to a larger group with different headers, etc). I believe this can be done via STDIN, and saw a post a long while back, but have no idea how to get the email as a variable i can slipt and play with. Any help appreciated. Justin French indent.com.au