> ## Documentation Index
> Fetch the complete documentation index at: https://docs.letterbucket.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Lockouts

> Temporary blocks after repeated authentication or request errors.

To protect the API from abuse, repeated failures are temporarily blocked.

## Authentication failures

Repeated authentication failures (missing, invalid or expired keys) are temporarily blocked.
While blocked, requests return `429` with a `Retry-After` header indicating how long to wait
before retrying.

## Request errors

Repeated client errors (`4xx`) on `POST`, `PUT` and `PATCH` requests are also temporarily
blocked. Successful requests, rate-limit responses (`429`) and authorization errors
(`401` / `403`) do not count toward this block.

<Note>
  When you receive a `429`, respect the `Retry-After` header before retrying, and fix the
  underlying error (bad key, malformed payload) rather than retrying the same failing request.
</Note>