no content when sending mail to a program via .forward

I'm writing a program that will take email based searches,
.forward seems
like the simplest way to accomplish this.
The problem that I am having is that I don't know how to
access the content
of the email. I tried argv and env but neither gave me a
clue on how to
access the actual message. I know there has to be a way to
do this since
this is the way procmail works. Can anyone give me an idea
of where do look
for the message data?

the variables I found were:

CLIENT_ADDRESS=
PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/X11R6/bin:/usr/local
/bin
SHELL=/bin/ksh
USER=search
HOME=/home/search
RECIPIENT=searchdomain.com
MAIL_CONFIG=/etc/postfix
CLIENT_PROTOCOL=ESMTP
CLIENT_HELO=domain.com
DOMAIN=domain.com
LOCAL=search
SENDER=johnbrahy.com
LOGNAME=search