Once you have determined that the e-mail you have received qualifies as 'spam', the next step is to determine if there has been a violation of the CAN-SPAM act.
Some of the violations involve fraud and related activity, such as someone who knowingly or conspires to:
1) Access your and/or another person's computer without authorization and sending the 'spam' messages from the unauthorized computer(s).
2) Send a 'spam' message with the intent to deceive or mislead recipients or any Internet access service as to the origin of such messages,
3) Falsify header information in the 'spam' message,
4) Use false identities for five (5) or more e-mail / online user accounts or two (2) or more domain names and intentionally sending the 'spam' messages from any combination of such accounts or domain names, or
5) Falsely representing themselves to be the registrant or the legitimate successor in interest to the registrant of five (5) or more IP addresses and sending ore-mail from such addresses.