The one thing that I got out of this was that NSA has no trouble at all reading and decrypting encrypted Internet traffic. Pretty much every mail exchanger operating today uses TLS for communications with clients and other mail exchangers. It's almost a certainty that these communications were encrypted, but NSA (illegally) produced them very quickly.
They could have simply read emails stored on servers of the email provider in plaintext, or have used keys handed over to them.
People rarely use end to end encryption. If it’s not e2e, somebody else, and thus NSA too, has the keys.