---
features:
  - |
    Support for dead letter queue is added for MongoDB, Redis and Swift. With
    this feature, message will be moved to the specified dead letter queue if
    it's claimed many times but still can't successfully processed by a client.
    New reseved metadata keys of queue are added: _max_claim_count,
    _dead_letter_queue and _dead_letter_queue_messages_ttl.