Looking at the headers, you should be able to tell every mail server the message touched. For example:
Delivered-To: ericjln@gmail.com
Received: by 10.239.137.15 with SMTP id j15cs159695hbj; Mon, 1 Feb 2010 07:57:34 -0800 (PST)
Received: by 10.224.83.85 with SMTP id e21mr2070265qal.227.1265039847481; Mon, 01 Feb 2010 07:57:27 -0800 (PST)
Return-Path:
Received: from bmsmail5.ieee.org (bmsmail5.ieee.org [140.98.193.25]) by mx.google.com with ESMTP id 7si11544910qyk.54.2010.02.01.07.57.26; Mon, 01 Feb 2010 07:57:27 -0800 (PST)
Received-SPF: neutral (google.com: 140.98.193.25 is neither permitted nor denied by domain of SEMA-CR--X4OZK@bmsmail2.ieee.org)
client-ip=140.98.193.25;
Authentication-Results: mx.google.com; spf=neutral (google.com: 140.98.193.25 is neither permitted nor denied by domain of SEMA-CR-1-IX4OZK@bmsmail2.ieee.org) smtp.mail=SEMA-CR-1-IX4OZK@bmsmail2.ieee.org
Received: from sbnaom1.ieee-res.ieee.org (dct1-lb-191-papp1.ieee.org [140.98.191.254]) by bmsmail5.ieee.org (8.13.8/8.13.8) with ESMTP id o11FrAg1003597 for ; Mon, 1 Feb 2010 10:57:24 -0500
Date: Mon, 1 Feb 2010 10:57:24 -0500
Follow the Received lines. We can see the message bounced around some internal google servers (10.239.137.15 and 10.224.83.85), that google got the message from bmsmail5.ieee.org [140.98.193.25], but that the first smtp server to send the message was dct1-lb-191-papp1.ieee.org [140.98.191.254]