All services is unsafe. Proton Mail and Tutanota too. Probably you don't understand what I want you to say. There are no safe services. If you and me don't have any information that some service has given a private correspondence of its users to the police or special services, it doesn't mean that this service is safe. Are you sure that Protonmail or Tutanota will not be in same situation as Hushmail? This could happen in any time. Don't need to embrace yourself with a fancy hopes.

Unfortunately you don't see my main idea, but is is very simple:

1. If you trust the storage of your private key to any service then there couldn't be any talks about safety
2. Use modern encryption algorithms with opened source code and private storage of private keys. Just this option provides a really safe communication.