I've had this dumb idea banging about in my head for a while: A pay-for e-mail service, working just like any other e-mail service (IMAP, POP3, etc.), except you can only e-mail (send AND receive) other folks on the same service.

Then, if companies do want to reach folks on this e-mail service, monetize it by forcing companies (for $$$) to use ONE address (on the same service, obvs) to reach the other folks on said service.

E.g. if you're the GOP and you want to reach jane@magical-email-service.com, you'll be sending e-mails ONLY from gop@magical-email-service.com, which in turn allows Jane to easily filter out the trash (instead of the e-mail coming from trump2024@, trump2030@, voteplz@, campaign-ohio-8827727-test-funnel@, etc.)

I have not thought this fantastic idea through.