Are you a user of Yahoo Mail?

According to Reuters, Yahoo built a special tool to scan their customers’ emails for specific information and then turned that information over to federal agencies.

The company complied with a classified U.S. government demand, scanning hundreds of millions of Yahoo Mail accounts at the behest of the National Security Agency or FBI, said three former employees and a fourth person apprised of the events. Some surveillance experts said this represents the first case to surface of a U.S. Internet company agreeing to an intelligence agency’s request by searching all arriving messages, as opposed to examining stored messages or scanning a small number of accounts in real time.

We don’t yet know what the snoopers were looking for in the Yahoo Mail dragnet nor do we know if any other email services were also working with the feds.

Apparently, the decision to comply with this constitutionally questionable request caused some controversy at Yahoo and may have influenced former Chief Information Security Officer Alex Stamos to jump ship and head over to Facebook.

Yahoo gave a terse, ambiguous statement to Reuters: “Yahoo is a law abiding company, and complies with the laws of the United States.”

Questions to the government about the snooping project were directed to the Director of National Intelligence, who declined to comment. The original directive ordering the snooping came in the form of a classified directive, so it’s no surprise the agency has no comment.

One notable thing about this particular snoop operation is the broad, real-time nature of the job.

“I’ve never seen that, a wiretap in real time on a ‘selector,'” said Albert Gidari, a lawyer who represented phone and Internet companies on surveillance issues for 20 year. “It would be really difficult for a provider to do that,” he added.

Google and Microsoft said they were not conducting any email searches for the federal snoop agencies. A Microsoft spokesperson said in a statement, “We have never engaged in the secret scanning of email traffic like what has been reported today about Yahoo.” Microsoft did not say whether or not it had received any request to do so.

“It is deeply disappointing that Yahoo declined to challenge this sweeping surveillance order, because customers are counting on technology companies to stand up to novel spying demands in court,” Patrick Toomey, an attorney with the American Civil Liberties Union, said in a statement.

People familiar with the situation say that Yahoo complied with the “request” because it thought it would lose if it put up a fight. Do you believe them?