To find if this is a registered Domain name, go to Spam Patrol go to "Resources" and use "InterNIC Whois Information" to find the Domain name. Alternatively you can also take the number found in your spam mail header and paste it into your web browser's location: or go to: address line and see where it takes you. This should be the website of the Domain from which your spam mail originated.
If you do not find an email address to which you should report spam abuse, then you can go to the Network Abuse Clearinghouse and use the "web look-up page". To report spam you can usually use either of the following: abuse@domain_name.com or postmaster@domain_name.com.
Then simply send an email to this address. Include the Full Header,
message and the subject line of the spam you received. You can put "spam" as the subject, and include a short note like the following:
The enclosed is unsolicited commercial e-mail, which is annoying and unwanted here. It is being forwarded to you because your system name or that of a system for which you are a listed system admin appears in the headers or as a reference in the text. Please take whatever steps are necessary to prevent this person from sending more of these. Thank you.
An additional warning: It is best not to respond to the links or addresses within a spam email. This just tells the spammer that yours is a valid email address and could result in more spam.
To find out more and to help fight spam, have a look around the following