Well, if I remember correctly (so if you try this, make some backups!!) the headers are normally separated by a "\n\n" type of double line break. So the formatted message should be:
From: user@email.com
To: user2@mail.com
Content-Type: text/html
Subject: Something Funny
Hey buddy... this email isn't that funny is it?
So, the body starts after the headers, and is separated by an empty line (99% of the time). So, just use a substr() to actually just extract the message:
// assuming $msg holds the current email
$msg = trim(substr($msg, strpos($msg, "\n\n")));
Then, just echo out $msg...
I'm 99% sure that will work... or something like that.
~Brett