To add onto what Andromxda said, SimpleLogin is included with your Proton account (might be paid accounts only).

Use it with a custom domain - it’s amazing and if Proton Mail ever shuts down you won’t have to migrate any of your logins because they’re already on your own domain.

Does the creative commons licence at the end of every comment really do anything? Are you going to do anything about it if someone doesn’t respect the permissions you’ve laid out?