A mailbox — the thing messages are delivered to.
Two kinds, both stored in this one table:
"user"— a personal mailbox owned by exactly one PhoenixKit user.owner_uuidis set and there is at most one per user (enforced by a partial unique index in the migration)."shared"— a team mailbox (support,sales, …).owner_uuidis the user who created it; everyone else reaches it through aPhoenixKitInbox.Schemas.MailboxGrant.
address is the mailbox's identity inside the app ("support@example.com",
or the owner's login email for a user mailbox). Inbox is an internal
messaging system — nothing is sent to the outside world through this
address, it is a display/lookup handle only. Outbound delivery to a real
inbox happens, if at all, through PhoenixKitInbox.Notify.
Tables are created by PhoenixKitInbox.Migrations, never by this schema.