The capitulation of Google, Apple, Verizon (no surprise there), Facebook, and pretty much every large US corporation to the uber-government's cadre of spies means that there is really only one way to secure your email.
Encrypt it yourself. On your PC. Which you protect as best you can - not very easy to do, but you can at least make it (somewhat) more difficult.
Use PGP or GPG, and check the signatures on the downloads. Make a very strong passphrase, and keep it secret, keep it safe.
The truly paranoid among us (Are we paranoid when they really are out to get us?) will buy a cheap computer for a few hundred dollars, install PGP or GPG, and NEVER, EVER connect it to the internet. It's sole purpose is to write, encrypt, decrypt, and read messages that are transferred by sneakernet. The entire machine is locked down as tight as possible. No wifi. No ethernet port. The thumb drive used to transfer messages is wiped clean with
Eraser after each use, and no files except ASCII ciphertext are ever allowed on that thumb drive. Autorun is disabled, of course, on both the CD drive and the USB ports.
This will raise the bar so they would need to physically access your encryption PC to install a keylogger in order to read content of your mail, assuming you use good keys and passphrase. They can do that, but it involves a major escalation of time and resources, even with a rubber stamp prostitute star chamber allowing anything at all. Our main advantage is that there are a lot more of us than them. Even with unlimited money printing on their side, they can't afford to send thieves into every basement on the planet, or even in the nation.
We know that the NSA explicitly targets ALL encrypted communications, whether inside the US or otherwise, so understand that the very act of trying to protect your privacy is considered grounds for suspicion.
Relying on offshore servers and services, free or otherwise, strikes me as incredibly foolish. Few are even questioning the vacuuming of ALL communications where one party is not a US citizen. If you send traffic to Germany, or Iceland, or any other foreign server, you can count on it being monitored, recorded, and cataloged. Whether they can break the encryption is not important. Traffic analysis works, and by encrypting comms to an offshore entity, you start out with two strikes against you.
Remember that once they decide you are interesting,
no amount of encryption will save you.
The nail that stands up gets pounded down. Be careful.
Peace,
Silver