The Federal Trade Commission (www.ftc.gov) is supposed to help you eliminate spam mails. Forward Spam to: This email address is being protected from spambots. You need JavaScript enabled to view it., in the subject line enter something like "unsubscribe link results in more Spam", "unwanted Spam message", "no unsubscribe link" or something similar.

When the FTC gets your mail, they will look into the matter and when they find out whom the spamming source is, they will take legal actions.

http://www.ftc.gov/bcp/conline/edcams/spam/index.html