NEW YORK (CNN/Money) - The Federal Trade Commission charged a group of individuals and companies Tuesday with spamming sexually explicit advertisements that are against the law.

According to an FTC press release, the companies sent hundreds of thousands of e-mail advertisements for pornographic Web sites that did not contain the required "sexually-explicit" warning in the subject line. In addition, the FTC claims many of the e-mails revealed sexually explicit words or images in the subject line, before the recipient even opened the message.

In addition, the FTC said the advertisements did not include the required "opt-out" link to be removed from the e-mail list. As a result, thousands of people continued to receive the messages without their consent.

The FTC also claims the e-mails did not say there was a fee for their services up front in the advertisement. Customers who followed the links were not informed of the fee until after they had given their e-mail addresses.

"The law gives consumers a tool to control what comes into their in boxes," Lydia Parnes, Acting Director of the FTC's Bureau of Consumer Protection, said in the press release. "Spammers beware! We are on the side of parents and kids to protect their ability to filter out sexually-explicit e-mails."

A federal judge has issued a temporary restraining order against the defendants that prohibits them from sending similar e-mails and freezes their assets, pending a preliminary hearing.

Named in the suit are Global Net Solutions, based in Las Vegas; Global Net Ventures, Ltd., based in London, England; Wedlake, Ltd, allegedly based in Riga, Latvia; Open Space Enterprises, Inc., based in Las Vegas; Southlake Group, Inc., based in Las Vegas; WTFRC, Inc., doing business as Reflected Networks, Inc., based in Las Vegas; Dustin Hamilton; Tobin Banks; Gregory Hamilton; Philip Doroff; and Paul Rose.