Outbox
FollowerSet

Inbox

Actor
    name      Text
    desc      Text
    createdAt UTCTime
    inbox     InboxId
    outbox    OutboxId
    followers FollowerSetId
    justCreatedBy ActorId Maybe
    errbox    InboxId

    UniqueActorInbox     inbox
    UniqueActorOutbox    outbox
    UniqueActorFollowers followers