Owner of Happy
End-to-end encrypted (E2EE) email doesn't benefit you and can be worse than not having it at all. Let's back this up with some facts: Encrypted emails must always be downloaded on all devices (this is because it isn't searchable by the server, barring some fancy academic solutions no-one bothers with). The "cloud" is just a backup solution. Every email you send or receive exists unencrypted in the other party's inbox.* The server still has access to unencrypted email at send/receive time (technically none of it is truly E2EE - more on this below). Using your preferred email client is hard or impossible (no POP3/IMAP, see 1.).
Compare this to simply using good old POP3. It actually provides the maximum level of privacy, and is equivalent to an E2EE email service when used with local full-disk encryption. Encrypted services receive plain emails, encrypt them, then discard the plain copies. With POP3, the server receives the plain email, you then download it via POP3, and it is deleted from the server (if following protocol). Privacy-wise, the end result is the same.
Except - with POP3 you gain the freedom to secure your emails with your choice of local disk encryption. You "own" your emails forever, and are free to search and analyse privately. Compare this to encrypted services where you must reach a cloud through proprietary protocols just to download your data (usually even advertised as a super premium "feature" behind a paywall).
