The Federal Anti-Spam law (Effective January 1, 2004) requires that you have implicit permission to send a commercial email to a new prospect that promotes a product or service-for-pay. Your valid postal mailing address must also be present in all mailings. If the prospect notifies you by messaging back to be removed, you must honor their opt-out request within 10 days as indicated in the 2004 Anti-Spam law.
Note that the web site you are sent to when you open unsolicited commercial email (SPAM) is rarely the domain which sent the SPAM. Reporting the web page to SPAM filtering services does not get SPAM filters improved. The domain to report is in the email header, not the email body.
Figuring out the header: How do I get my email program to reveal the full, unmodified email? Interpret the results using http://mxtoolbox.com/EmailHeaders.aspx or the “Message Analyzer” tab of https://testconnectivity.microsoft.com/.
Defend against SPAM with MailWasher.
URIBL.COM is a service that distributes information about domain names as they are related to email, primarily Unsolicited Bulk/Commercial Email (UBE/UCE). URIBL.COM serves this information via Public DNS, RSS Feeds, as well as local Data Feeds via rsync. Our data is used primarily to complement your existing Anti-Spam software. URIBL is enabled by default in the popular open source SpamAssassin software and several other commercial offerings.
Other SPAM advice at AdOut.org.