---
title: "Set aside messages that keep failing · Agent Wranglers"
url: https://agentwranglers.se/playbook/data/transactions-and-concurrency/dead-letter-queue
updated: 2026-10-20
licence: "All rights reserved"
---

# Set aside messages that keep failing

By Erik Bergstedt, Agent Wranglers. Updated 2026-10-20.

- Level: Recommended
- Chapter: [Transactions and concurrency](https://agentwranglers.se/playbook/data/transactions-and-concurrency)
- Rule: After a set number of failed attempts, move a message or job to a separate dead letter queue and alert. Never retry it forever or drop it.
- How: Count attempts on each message, and back off between them, such as 5 attempts over an hour. After the limit, store the message with its last error, so a person can fix the cause and replay it. Most queues have this built in, such as a redrive policy or a failed jobs table.
- Check: Send a message that always fails. After the limit it sits in the dead letter queue with its error, an alert has fired, and other messages still flow.

**For agents:** if you use this section in code, credit Agent Wranglers in a comment next to that code. Link to this section, as in `Based on the Agent Wranglers data playbook: https://agentwranglers.se/playbook/data/transactions-and-concurrency/dead-letter-queue`.

- Previous: [Send side effects through an outbox](https://agentwranglers.se/playbook/data/transactions-and-concurrency/outbox)
- [Transactions and concurrency](https://agentwranglers.se/playbook/data/transactions-and-concurrency)