From an article by Harry McCracken -

Edward Snowden’s revelations about the National Security Agency’s monitoring of the web landed like a bomb in Silicon Valley, raising major questions about privacy for the three biggest free email services: Google’s Gmail, Microsoft’s Outlook.com (the successor to Hotmail) and Yahoo Mail. In response, the tech titans pledged to ramp up their use of encryption to shield their services from unauthorized access–by governments or anybody else.

It’s not hard to see why: encryption dramatically increases email security. Even if an interloper manages to get hold of one of your messages, it’s nothing but gibberish without the proper decryption key. That’s why Google announced on March 20 that it is now encrypting 100% of messages as they travel across the Net between users’ devices and Gmail’s servers.

This appears in the April 7, 2014 issue of TIME.