It's funny that people would flee from Gmail to other third-party mail providers out of privacy concerns, because it suggests they think their biggest privacy concerns are the NSA. But that's not true; in practice, you have much more to fear from criminals than the government; you can use simple means/motive/opportunity reasoning to arrive at this conclusion.

Meanwhile: no mail provider in the world has invested more resources in security than Google Mail. Google spends millions of dollars to ensure the security of the Google Mail platform. It also runs a public-facing bounty program --- one of the oldest and most reputable --- to solicit more vulnerabilities. It staffs a large and extremely well-regarded software security team to keep up with vulnerability classes and to research new ones.

Can you say the same thing about Fastmail.fm?