If I read your original post correctly you have a file in Unix "mbox" format, where each message starts with something like

From MAILER-DAEMON@gw.peppler.org  Thu Sep 16 17:29:10 2004
Return-Path: <MAILER-DAEMON@gw.peppler.org>
Received: from ntexchsrv.ilstmd.ins (ntexchsrv.ismis.com [12.2.26.87])
        by gw.peppler.org (8.12.10/8.12.10) with ESMTP id i8GLT9n60041
+56
        for <junk@peppler.org>; Thu, 16 Sep 2004 17:29:09 -0400
From: postmaster@ismie.com
To: junk@peppler.org
Date: Thu, 16 Sep 2004 16:29:45 -0500
... rest of headers ...
[download]

AFAIK this is what Mail::Box::Mbox and Mail::MboxParser are built to handle.

You can also build your own parser, of course, but you have to be careful not to get tripped up by any "From " strings that might be embedded in messages...

Michael Michael