As I’m sure you’ve experienced, spam (junk email) is a huge problem. If you have an email address than you’ve probably received junk. Most ISPs now try to run services on their mail server to stop this, but some always get through. If you get spam and want to report it yourself, a good place to start is with SpamCop:
SpamCop is the premier service for reporting spam. SpamCop determines the origin of unwanted email and reports it to the relevant Internet service providers. By reporting spam, you have a positive impact on the problem. Reporting unsolicited email also helps feed spam filtering systems, including, but not limited to, SpamCop’s own service.
You can report spam that you’ve received and SpamCop will contact the server administrator for you. It may be a tedious process, but every little bit helps. Check out SpamCop.net for more details.