DevOps Glossary

Dead Letter Queue (DLQ) is a message queue that stores messages a system cannot process successfully after one or more attempts. DLQ stands for Dead Letter Queue, and in practical terms it gives teams a controlled place to isolate failed messages so they do not block the main queue or cause repeated processing errors. A message may be sent to a DLQ because it has invalid data, exceeds a retry limit, times out, references a missing resource, or triggers an application error. Engineers can inspect the failed payload, review error metadata, fix the root cause, and then retry, replay, archive, or discard the message. DLQs are common in event-driven systems, background job workers, and cloud messaging services such as Amazon SQS, Google Cloud Pub/Sub, Azure Service Bus, Apache Kafka, and RabbitMQ.