A dead letter subscription is subject to the same permission requirements as a regular subscription. That is, a client can receive dead letters for only the events on its can-subscribe list. If a client specifies an event type using wildcard characters, that client will receive only those dead letters that coincide with its can-subscribe list.

Persistence of dead letter events is determined by the normal rules of client types and event types.

Dead letter subscriptions apply to both published and delivered events. If the Broker receives a delivered event that has been addressed to a non-existent client, the Broker will deposit that event in the dead letter queue if one exists for the event type.