http://emailtrackerpro.visualware.com

Here by the company that sells VisualRoute(once free), you can trace an email to its source by

• pasting in the email headers
• inputting any emailaddy

FAQ: Tracing Emails and Email Headers using eMailTrackerPro

Interactive Email Tracing Tutorial

NOTE: This uses javascript, and is not 100% anonymous.

you can effectively do the same using spamcop.org, all they want are donations to get no nag screens. try it out sometime. it's kind of like a fight back tool.

visualroute 2005 is a nice tool

yes but i thing nowdays it s unuseful to track email, there are too many spam emails. Furthermore you can specified an open relay server at http://www.ordb.org/, it s more useful and you will not lose time to check where is the spam server
For more security add an anti-spam service on your email server and you will more secure.