Not only that. It's still built around that ancient concept that users connect via TTYs to a single machine, and mail is actually moving mail locally to their /

Not only that. It's still built around that ancient concept that users connect via TTYs to a single machine, and mail is actually moving mail locally to their /var/spool/mail/%u, no network involved. In fact, this is also what all self-hosted email guides expect in Anno Fucking Domini 2022! I don't want to have to create system users just so they can have their mailboxes! Somebody tell those guys that such defaults are not sensible in this age.