Actually, the possibility of backtracking is very good, porvided you can get some co-operatin from the ISP
Looking at the header on my email messages, I see
Sender:
[email protected] Received: from colt-telecom.com (82-35-99-35.cable.ubr05.dals.blueyonder.co.uk [82.35.99.35])
by siaag2ad.compuserve.com (8.12.9/8.12.7/SUN-2.12) with ESMTP id i120T8EN015731
for <me>; Sun, 1 Feb 2004 19:29:12 -0500 (EST)
Message-Id: <
[email protected]>
The xxxx@colt -telecom is obviosly spoofed, but the IP address is genuine as far as I know - that is the 82.35.99.35
So, if Blueyounder both to read the emails I have sent to them, they can identify the machine easily.