Companies that sold web addresses that failed to work have agreed to settle Federal Trade Commission (FTC) charges and pay $300,000 (£191,000) to customers.
The FTC alleged that after 11 September 2001, the domain name sellers launched an aggressive spam campaign to advertise domains ending in '.usa'.
The companies were not accredited domain name registrars, said the FTC, and the '.usa' domain names cannot be used on the internet.
Subject lines in the emails read: "Be Patriotic! Register .USA Domains".
A hyperlink in the email connected consumers to a website where they were offered the advertised domain names for $59 (£38) each.
Four companies - TLD Network, Quantum Management (GB), TBS Industries and Quantum Management US - have agreed to repay customers $300,000 to settle the federal charges.
Cotton seedling freezes to death as Chang'e-4 shuts down for the Moon's 14-day lunar night
Fortnite easily out-earns PUBG, Assassin's Creed Odyssey and Red Dead Redemption 2 in 2018
Meteor showers as a service will be visible for about 100 kilometres in all directions
Saturn's rings only formed in the past 100 million years, suggests analysis of Cassini space probe data
New findings contradict conventional belief that Saturn's rings were formed along with the planet about 4.5 billion years ago