Lidzborski said that 100 percent of email messages that Gmail users send or receive are encrypted while moving internally. “This ensures that your messages are safe not only when they move between you and Gmail's servers, but also as they move between Google's data centers—something we made a top priority after last summer’s revelations,” he said.
Joseph Hall, chief technologist at the Center for Democracy and Technology, told AFP that Google's encryption "would make it very difficult" for the NSA or others to tap into email traffic directly. "I'm reluctant to say anything is NSA-proof," Hall said. "But I think what Google is trying to do is make sure they come through the front door and not the back door."
In December, Microsoft said it would “pursue a comprehensive engineering effort to strengthen the encryption of customer data” in order to protect its customers from prying eyes and increase transparency.