Dead letter queue (original) (raw)

In message queueing the dead letter queue is a service implementation to store messages that meet one or more of the following criteria: 1. * Message that is sent to a queue that does not exist. 2. * Queue length limit exceeded. 3. * Message length limit exceeded. 4. * Message is rejected by another queue exchange. 5. * Message reaches a threshold read counter number, because it is not consumed. Sometimes this is called a "back out queue". 6. * The message expires due to per-message TTL (time to live) 7. * Message is not processed successfully.