AmazingWill, in my opinion, if you want to ensure privacy, online service with IMAP is not the solution, because:

1) You don't know who has (or will get) access to the emails stored at the servers.

2) You don't know if your account will not be hacked.

In my opinion, you either need to:

a) host your own email server, or

b) periodically download your emails through pop3s to your own encrypted drive, not leaving them on the server