FastMail, ProtonMail, or an AWS server upon which your run your own email can also be disabled by the owner of that service. Unless you run your own on-premise

FastMail, ProtonMail, or an AWS server upon which your run your own email can also be disabled by the owner of that service. Unless you run your own on-premise server, that risk always exists. And even then, your ISP could block your server. There comes a point when the paranoia gets unreasonable.