The Federal Trace Commission Wednesday passed a rule calling for all pornographic spam to carry a warning label.

Now all spam that contains sexually explicit material must include the label ''Sexually Explicit'' in the subject line.

Spammers who don't follow the new law will face fines, civil law suits, and criminal penalties, including imprisonment and fines up to $250,000 for individuals and $500,000 for organizations.

The new rule was required by the Can-Spam Act, which Congress passed in 2003. The Act directs the FTC to adopt a law requiring a notice to be included in sexually oriented spam. The notice must be in the subject line, as well as in the electronic equivalent of a 'brown paper wrapper' in the message body of the email, according to a release from the FTC. The 'brown paper wrapper' will bear the warning but also will hide any other images or information.