An exception destination is the location where messages that are not delivered to their original intended destination are sent for safekeeping. Exception destinations prevent the loss of messages that fail to get sent to their intended destinations.
You can also configure each bus destination so that it has a non-default exception destination. This enables administrators to access at a unique place messages that cannot be delivered for the bus destination. An exception destination must be a queue destination, but can be either local or remote. The exception destination must already exist before you configure another bus destination to use that exception destination. If the exception destination is not a queue, or if it has been deleted when the message arrives, undeliverable messages are rerouted to the default exception destination for the messaging engine.
The service integration bus cannot guarantee the ordering of messages sent to an exception destination. Because of this, if message order is important, you can configure a bus destination so that it does not use an exception destination. In this case, the Maximum failed deliveries limit specified for the destination is ignored, and the message remains available to consumers. Synchronous consumers repeatedly attempt to get the message; message-driven beans and other asynchronous consumers repeatedly attempt consume the message. This situation continues until either the message is removed from the destination (for example, by an administrator using the WebSphere Application Server administrative console) or if the consumer is subsequently able to process the message without rolling back.
Published messages are discarded if there are no subscribers.
For related information, see Specifying an exception bus destination.