Today's revelations that the National Security Agency collected bulk data on the email traffic of millions of Americans provides startling evidence for the first time to support a whistleblower's longstanding claims that AT&T was forwarding global internet traffic to the government from secret rooms inside its offices.

The collection program, which lasted from 2001 to 2011, involved email metadata — the "enveloped" information for email that reveals the sender's address and recipient, as well as IP addresses and websites visited, the Guardian newspaper reported today.

Mark Klein, a retired AT&T communications technician, revealed in 2006 that his job duties included connecting internet circuits to a splitting cabinet that led to a secret room in AT&T's San Francisco office. During the course of that work, he learned from a co-worker that similar cabins were being installed in other cities, including Seattle, San Jose, Los Angeles and San Diego, he said.

The split circuits included traffic from peering links connecting to other internet backbone providers, meaning that AT&T was also diverting traffic routed from its network to or from other domestic and international providers, Klein said.

That's how the data was being vacuumed to the government, Klein said today.

"This is a complete vindication," Klein, a San Francisco Bay area retired man, said in a telephone interview.

Attendees break for lunch during the 2012 Republican Convention in Tampa, Fla. on Tuesday, Aug. 28, 2012. Photo: Tristan Spinski Mark Klein. Photo/Wikipedia

WIRED was leaked and subsequently published Klein's documents detailing the spying equipment in 2006, when he said an NSA agent showed up years before to interview a management-level technician for a special job.

Klein's documents were lodged under seal in an Electronic Frontier Foundation lawsuit accusing the government of siphoning Americans' communications to the NSA.

"This is exactly what we've been arguing in court for years," Trevor Timm, an EFF digital-rights analyst, said in a telephone interview.

The documents, in part, fueled the lawsuit that so scared Congress that lawmakers passed legislation immunizing AT&T and any other telecommunications companies from being sued for assisting the NSA's dragnet surveillance program.

"They are collecting everything on everybody," Klein said.

After Congress killed the litigation, the EFF sued the government instead. That case is pending in a San Francisco federal courtroom.