Email is insecure. Protonmail is no less private than any other normal email host. Its convoluted e2ee setup may be more private. You can selfhost just IMAP

Email is insecure. Protonmail is no less private than any other normal email host. Its convoluted e2ee setup may be more private. You can selfhost just IMAP storage, and pay an email service provider to receive and store your mail for you, periodically archiving it to your own long term storage and removing it from the provider.