Phil Zimmerman YouTube/InternetSocietyVideo Silent Circle, a company founded by Internet Hall of famer Phil Zimmermann, famous privacy expert Jon Callas, and a couple of Navy Seals, has shut down its secure email service.

They shuttered it because email can't be secured in a way that would prevent a government agency like the NSA from snooping, the founders said.

All email messages "leak metadata" they say. That information includes data about who you are talking to and where you are. That info is visible even if the message itself is encrypted.

"E-mail as we know it today is fundamentally broken from a privacy perspective," Callas says. That's a pretty strong statement coming from this particular guy.

Zimmermann and Callas were the creators and cofounders of Pretty Good Privacy in the 1990s. PGP was one of first technologies to encrypt email to prevent spying.

Last year, they launched a new service, Silent Circle, that encrypts mobile phone calls, video calls and texts. Since smartphones also handle email, Silent Circle was encrypting email.

But now it's pulling the plug on the email portion of their service. The company says that it has not been asked to add a back door or to turn over emails. It is closing the service preemptively.

If you want to see what someone can learn about you by looking at your email metadata, here's a tool called Immersion that will show you. It was created by a team at the MIT Media Lab.