Congress approved new legislation Monday that would control the distribution of unsolicited e-mail, a measure that represents the federal government’s increased efforts to regulate America’s technology industry.

The “can spam” legislation requires unsolicited e-mails to include a mechanism so consumers can opt out of receiving the mass mailings. Experts on the issue warn that consumers will have to change their behavior in dealing with spam.

The measure prohibits senders of unsolicited commercial e-mail from disguising their identity by using a false return address or misleading subject line. Senders are also not allowed to harvest addresses off websites.

The U.S. House of Representatives voted in favor of approving slight changes to the Senate’s version of the legislation last month. The bill supersedes tougher anti-spam laws that have already passed in some states, including a California law that is to take effect Jan. 1.

This legislation also encourages the Federal Trade Commission to create a “do-not-spam” list of email similar to the nation’s “do-not-call” list that targets the telemarketing industry. The anti-spam list outlines penalties for spammers of up to five years in prison in specific circumstances.

However, some question how the law would be implemented, considering most spammers are hard to identify and live overseas. Other critics said the bill does not go far enough to discourage unwanted e-mails.

The Coalition Against Unsolicited Commercial E-mails described Congress’s efforts as “really disappointing.” They prefer provisions that require marketers to obtain a user’s permission before sending them any mass mailings.

“This bill does not stop a single spam from being sent. It only makes that spam slightly more truthful,” CAUCE Chairman Scott Mueller said in a statement.

The anti-spam legislation is among the farthest-reaching Internet measures approved under the Bush administration, which had followed former President Clinton’s hands-off approach toward regulating this industry. The last major technology legislation was passed in 1998, banning websites from collecting personal information from children under 13.

According to the Associated Press, President Bush indicated that he intends to sign the bill into law, especially after the flood of spam the White House received through its system this summer.