As seen in the case of tormail, even if a service is currently not on the "prism list", the service still can be compromised later on. Also keep in mind that all parties' providers must be secure. The best candidate for scenario is actually bitmessage, or PGP. Neither of them rely on a centralized provider, so there's nothing to raid.
I'm not looking to be total dark - I want something relatively simple (no tormail) but that isn't known to be signed up with NSA, or unlikely to do so. Also as a protest toward Google and others.
I could set up my own domain and do pop3 no?