The final regulations, which followed months of public comment, are substantially similar to regulators’ original proposal completed in April.
But the final rules now define what constitutes a commercial email message when the recipient has a “relationship” with the sender.
Factors relevant to the FTC’s interpretation include the placement of commercial content in whole or in substantial part at the beginning of the body of the message; the proportion of the message dedicated to commercial content; and how color, graphics, type size and style are used to highlight commercial content.
The FTC, in its final rulemaking, emphasized that it does not intend to regulate noncommercial speech.
The United States is responsible for exporting 43 percent of all spam and leads a list of the top 12 spam-producing nations, according to an August study by antivirus company Sophos.
In April, the FTC filed its first lawsuits under the Can-Spam Act, which took effect in January.
The first suit accused four Detroit-area men of leading a spam operation that marketed diet patches in emails with fake addresses.
The second FTC case involved an Australian company, Global Web Promotions, which marketed human growth hormone products in emails that disguised their source.
A third case involved a Boca Raton, Fla., spammer who bombarded email users with pitches for human growth hormone products, such as Supreme Formula HGH and Youthful Vigor HGH.
Finalized rules of the Can-Spam Act can be found here.