How to Build a Dead Letter Queue System for Reliable Data Processing

Every data processing system will eventually receive a record it cannot handle. A missing required field, an unexpected data type, a payload that exceeds size limits, a downstream service that rejects the record with a non-transient error. What happens to that record determines whether your system is reliable or merely operational. A dead letter queue (DLQ) is the mechanism that handles unprocessable records without stopping the rest of the pipeline. Instead of retrying indefinitely or dropping