Washington ? Internet users skeptical of junk e-mails promising easy money, miracle cures and dream dates are right to be wary: The government says two-thirds of the “spam” messages clogging online mailboxes probably are false in some way.

The Federal Trade Commission said Tuesday that spam e-mails involving investment and business opportunities are especially dubious, with an estimated 96 percent containing information that probably is false or misleading.

The FTC studied a random sample of 1,000 unsolicited e-mails taken from a pool of more than 11 million pieces of spam it has collected. The agency looked for deceptive claims in a message’s text or the “from” or “subject” lines.

“In one way or another, a great deal of it appears to contain important information that is false or deceptive,” said Eileen Harrington, the FTC’s director of marketing practices.

As with telemarketing and other types of advertising, false claims and fraud are at the fringes of the business, Harrington said, but with spam, “there is far more deception in this medium than there is in others.”

Twenty percent of the spam studied involved business opportunities such as work-at-home and franchise offers. Offers for pornography or dating services accounted for another 18 percent. Spam involving pitches for credit cards, mortgages and insurance was the third largest category at 17 percent.

The FTC plans a three-day forum beginning today to discuss how the government and businesses should deal with spam.