How does Azure Service Bus guarantee message delivery reliability?

Azure Service Bus ensures at-least-once delivery using message locks, retries, and dead-letter queues.

Service Bus guarantees message delivery by persisting messages durably until they are explicitly completed. In PeekLock mode, messages are locked for a consumer and only removed after successful processing. If processing fails or the lock expires, the message becomes available again. Retry policies and DLQ ensure no message is lost even in failure scenarios.