how about all alumni email addresses just become forward and reverse proxy relays. let me just add a forwarding address, and provide outbound mail.

permanent vanity addresses tied to accomplishments, clubs etc should be a straightforward business or product for google, microsoft, cloudflare etc to offer.

or patch dns to allow the sale of email addresses, and process all forwards (with the forwarding address stored privately) before processing other mx records.

none of that should take up much storage.