Email systems that feature encryption sending and receiving messages have been for the most part difficult use and sometimes expensive. ProtonMail is easy to setup and use and features a free plan that is generous enough for occasional use and the paid plans are reasonable.
End-to-end encryption works other users of the service. You can password protect messages to non-users and set expiration dates on messages. It’s a great service for anyone concerned about securing some or all of their email transactions.