@Ralph Haygood The problem with foreign email services is we know from Snowden that the government basically treats foreign communication as OK to intercept even without a request. So, weirdly, US-based services could be more secure. I assume the reason Silent Circle has Angwin's approval is the method of transmission doesn't require Silent Circle keeping data.
@libelle So, Angwin discusses some email options in the book. But the problem as I understand it is none of them can guarantee protection from wiretap requests, some as blanket as "hand over your keys so we can de-encrypt communications." And so these services often shut down without warning, to protect your data. Which is not the end of the world if you are backing up, I suppose.
Encrypting email herself is something experts warned her against, because it relies in part on people you communicate with.
But I'll go back to that section of the book, and see if there's something that's the best of the imperfect solutions.