DM News: FTC Requires Label for Sexually Explicit Spam
CNET: FTC: Porn spam must be labeled

While the Internet has been waiting for the Federal Trade Commission (FTC) to introduce regulations to help in the spam battle, the FTC appears instead to have been focusing on porn. The Commission issued a mandate that by the middle of May, porn spammers must use a subject line that includes " Sexually-Explicit:". Just to make sure that there is a potentially valid constitutional challenge, they also limited porn companies in their ability to publish certain types of images within the emails.

If the FTC, along with the Justice Department, plans to enforce this measure as strictly as they have with the Can-Spam Act's anti-spam provisions, then the porn companies have very little to worry about.