This is the name of the default DLQ (Dead Letter Queue) the server peer will use for destinations. The DLQ can be overridden on a per destination basis - see the destination MBean configuration for more details. A DLQ is a special destination where messages are sent when the server has attempted to deliver them unsuccessfully more than a certain number of times. If the DLQ is not specified at all then the message will be removed after the maximum number of delivery attempts. The maximum number of delivery attempts can be specified using the attribute DefaultMaxDeliveryAttempts for a global default or individually on a per destination basis.