Given the fact that technology here in the US, Canada, and Europe has advanced at a faster pace then say, Singapore, I can assure you that most commercial spammers don't send from US based accounts. It is not uncommon for me to get spam from Singapore, Cypress, Lavos, Siam, Korea, and Taiwan. So a spammer can bounce his e-mails off one, two, sometimes three of these 'wide open' servers and do so quite anonymously. That is unless you have a friend who works at the CIA and owes you a big favor. Do not spend time and energy on spammers.
Spammers are energy creatures.
Don't feed them and they will die. Now there are some of you out there who are, believe it or not, impervious to spam. The .ORG accounts are non-profit organizations. Spammers won't waste their time on you. Now you .MIL folks, you have it made.