You won't find United Airways or U.S. Airlines at any U.S. airport, yet letters with those names are appearing in millions of mailboxes offering recipients free tickets worth more than $1,000.
The Better Business Bureau says it's a phishing scam intended to steal consumers' personal information.
The names on top of the letters are remarkably similar to that of U.S. Airways and United Airlines -- but neither is a registered airline.
When we called the phone number on the mailer and identified ourselves as news reporters the operator was cagey. He ultimately parked us in voice mail.
Erica Der with the Florida Department of Agriculture and Consumer Services was highly suspicious when we showed her the mailers.
"[There's] zero percent chance you'll be able to find United Airways," she said.
We spent about a month trying to find the source of the letters.
On our second call, an agent in Arizona agent allowed us to record his voice. He explained that the mailers are for a "promotion" offered by a travel agency called Direct Vacation Deals. He said a 90-minute sales presentation was required to receive the airline tickets.
When pressed about the names of the counterfeit air carriers, he said the company has agreement with major carriers.
"We work in conjunction with the airlines," he said.
United said it has no relationship with the letters. U.S. Airways said the flyer is fraudulent.
Next, we learned the presentations take place at an office building in Orlando. There were discovered a locked door and the name Global Vacation Network. Neighbor business said they were unsure what happens in the office and that they work "strange hours."
Through an attorney in Atlanta, Global Vacation Network distanced itself from the United Airways and U.S. Airlines mailers. It said a Miami marketing company called Prescient, LLC sends the letters.
The Prescient website was inoperable and redirected us to its hosting service. When we called Prescient we received an error message that it was a non-working number.
After e-mailing the company via a different website provided by Global Vacation Network, a representative contacted us. He immediately took credit for the letters.
John McCarthy claimed United Airways and U.S. Airlines are real companies that are part of Prescient, even though they are not registered with the Florida Division of Corporations.
McCarthy conceded that, despite their names, neither United Airways nor U.S. Airlines is an air carrier.
"Some people might confuse our company with the name of an airline," he said. "I can't help that."
McCarthy said the letters are designed to entice married couples to buy memberships in a travel club, with costs ranging from $1,500 to $7,000. He is unapologetic about his tactics.
"When I send out a letter that's talking about airline tickets, guess who calls me? People interested in travel," he said.
McCarthy said his company sent 25 million United Airways and U.S. Airlines letters in 2012. He said he received only eight complaints.
The Better Business Bureau website has more than 600 comments on its pages about the United Airways and U.S. Airlines letters. The BBB says the letters are a fraud.
Because the letters arrive without a return address, use a signature stamp, and feature the names of phony airlines, the BBB has concluded the letters are a phishing scam.
McCarthy railed on the BBB, calling it extortionist. He vehemently denied the fraud allegation.
"There is no phishing activity, it's never happened," he said. "We've never been accused of that. I've never heard about that before."
McCarthy said that if consumers have a problem with his letters, they don't have to call. He suggested skeptics throw it away.
Der, with consumer services, agreed. She said that calling just once gives a solicitor an in: your phone number.
"They'll continue calling," she warned.