Fact-checking John Oliver's interview with Edward Snowden about NSA surveillance

"Other experts pointed out that we don’t know for sure what happens to these exchanges when they are collected. Jonathan Mayer, a cybersecurity fellow at Stanford University’s Center for Internet and Society, said many important features of Upstream collection "haven’t leaked and remain classified," such as whether it involves bulk collection, massive-but-targeted collection or only individually targeted collection, he said.

Mayer, of Stanford University, suggested the odds are good that your message is stored domestically if you’re an American who is working within the continental United States and who is using Gmail. Mayer called Snowden’s example of an intimate picture shared between a couple in New York hitting a London server en route to its destination "hypothetically possible, but it’s unlikely." The route between providers would have to be unusual, and the connection would have to be unencrypted, he said.

"There are enormous privacy implications from the one-end foreign rule, to be clear," Mayer said. "I just don’t think this is a very generalizable example.""