Looking at the source header of the email, I found Return-Path: . The whois database shows that emsemail1.com is registered to:
Registrant: Domain Administrator PO Box 11478 Delray Beach, FL 33483 US
Registrar: DOTSTER Domain Name: EMSEMAIL1.COM Created on: 24-OCT-03 Expires on: 24-OCT-04 Last Updated on: 27-OCT-03
Administrative, Technical Contact: Administrator, Domain EMSEMAIL1.COMrZUmsM@privacypost.com PO Box 11478 Delray Beach, FL 33483 US 561-658-0833
Domain servers in listed order: NS1.EMSEMAIL1.COM NS2.EMSEMAIL1.COM
End of Whois Information
Search Google for EMSEMAIL, the first returns are about receiving spam from EMSEMAIL. So, Wes Clark's team is using a known spammer to send his message, even though his message complies with the CanSpam Act.
What is annoying is that your option to be taken off of the list appears at the bottom. You have to send a letter via US Postal Service. This is stupid. They spam you, and you have to take time to write a letter, buy a stamp, and put it in the snail mail. you just gotta love the CanSpam Act.