The problem of spam is a very serious one, and even more so in the case of e-mail messages that contain certain types of materials that should not be viewed by minors. That is one of the reasons why many state authorities are taking action against the companies that send such types of messages.

Thus, according to Reuters, five pornography companies have agreed to pay $1.16 million in fines for sending "spam" e-mail without a warning that it contains sexually explicit material, U.S. regulators said on Wednesday.

Three other businesses also face lawsuits for sending improperly labeled e-mail, the Federal Trade Commission said.

Under FTC rules, commercial e-mailers must include the phrase "SEXUALLY EXPLICIT" in the subject lines of pornographic messages to allow consumers to more easily filter them out, and the marketers also must ensure that the messages don't contain graphic sexual images when they are first opened up.

The companies targeted in the crackdown didn't actually send out the messages but are still liable because they hired others to do so, the FTC said.

According to the FTC, BangBros.com Inc. of Florida agreed to pay $650,000; MD Media of Michigan will pay $238,743, and APC Entertainment Inc. of Florida will pay $220,000. Pure Marketing Solutions and Internet Matrix Technology together will pay $50,000 to settle the charges.

The companies also agreed to allow the FTC to monitor their operations to make sure they comply with existing laws.

Three other companies also face lawsuits for improper labeling: TJ Web Productions, based in Nevada; Cyberheat Inc. of Arizona; and Impulse Media, of Washington State.