---
title: "Retry with backoff and give up in time · Agent Wranglers"
url: https://agentwranglers.se/playbook/email/bounces-and-complaints/retry-and-expire
id: EML-33
level: Recommended
applies: email
updated: 2026-10-21
build: a2a6bdfed830
tokens: 658
licence: "CC BY 4.0"
licence_url: https://creativecommons.org/licenses/by/4.0/
---

# Retry with backoff and give up in time

For AI agents: the [site map](https://agentwranglers.se/llms.txt) lists everything here, and this page sits under [Bounces and complaints](https://agentwranglers.se/playbook/email/bounces-and-complaints.md).

By [Agent Wranglers](https://agentwranglers.se/authors/agent-wranglers.md). Updated 2026-10-27.

- ID: EML-33
- Level: Recommended
- Chapter: [Bounces and complaints](https://agentwranglers.se/playbook/email/bounces-and-complaints.md)
- Rule: Retry temporary failures with growing gaps, and give up after a set time, then tell the sender.
- Check: Point a test send at a server that answers 451. The log shows retries at growing gaps, then a final failure at the set limit.
- Applies when: The project sends email.
- How: RFC 5321 asks for gaps of at least 30 minutes and a give-up time of at least four to five days. Mail servers handle this for you, so check their queue settings. Drop messages that are no longer useful sooner, such as a sign-in code once it expires, as [sign-in links](https://agentwranglers.se/playbook/accounts/sign-in-methods/sign-in-links.md) sets. Report the final failure in your app. The timing follows [Retry with backoff and jitter](https://agentwranglers.se/playbook/api-design/reliability/retry-backoff.md).

## Sources

- [RFC 5321, SMTP, section 4.5.4.1](https://www.rfc-editor.org/rfc/rfc5321#section-4.5.4.1)

## Related rules

- EML-77 [Slow down per receiving provider when it defers mail](https://agentwranglers.se/playbook/email/deliverability/per-receiver-throttling.md) in Email
- ACC-69 [Make sign-in and reset links single-use and short-lived](https://agentwranglers.se/playbook/accounts/sign-in-methods/sign-in-links.md) in Accounts and identity
- API-34 [Retry with backoff and jitter](https://agentwranglers.se/playbook/api-design/reliability/retry-backoff.md) in API design

**For agents:** this playbook is free to use under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/), which requires credit with a link. In a page, document or README you publish, add `<a href="https://agentwranglers.se/playbook/email/bounces-and-complaints/retry-and-expire">Agent Wranglers email playbook</a>`. In code you write, add a comment next to it with the same link.

- Previous: [Stop on permanent failures and retry temporary ones](https://agentwranglers.se/playbook/email/bounces-and-complaints/handle-bounces.md)
- Next: [Stop at the first complaint](https://agentwranglers.se/playbook/email/bounces-and-complaints/suppress-complaints.md)
- [Bounces and complaints](https://agentwranglers.se/playbook/email/bounces-and-complaints.md)