At this point I'm too afraid to ask what the outbox model is.
Discussion
Nip65
L2 scaling solution for nostr
people used to call it the gossip model before, it's basically the same thing.
it's a way for smaller relays to get notoriety, basically to oversimplify by publishing a kind 10002 event to bigger relays, as described in NIP-65, you can mark your relay preference to any client that looks at those big relays