In message queueing a dead letter queue (DLQ) is a service implementation to store messages that the messaging system cannot or should not deliver.
[1] Although implementation-specific, messages can be routed to the DLQ for the following reasons: Routing these messages to a dead letter queue enables analysis of common fault patterns and potential software problems.
[7] If a message consumer receives a message that it considers invalid, it can instead forward it an Invalid Message Channel,[8] allowing a separation between application-level faults and delivery failures.
Queueing systems that incorporate dead letter queues include Amazon EventBridge,[9] Amazon Simple Queue Service,[7] Apache ActiveMQ, Google Cloud Pub/Sub,[10] HornetQ, Microsoft Message Queuing,[2] Microsoft Azure Event Grid and Azure Service Bus,[11] WebSphere MQ,[12] Solace PubSub+,[13] Rabbit MQ,[5] Confluent Cloud[14] and Apache Pulsar.
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