# POST /api/v1/inboxes/:id/rules

Auth: Bearer

HTML: https://cooperemail.com/docs/reference/create-rule

## Summary

Create a rule. Conditions are AND and case-insensitive: from (email, @domain, or domain), to, subject_contains, body_contains, has_attachment, auth pass|fail (DMARC), and list. Actions: add_labels, folder (inbox, archive, spam, trash), mark_read, forward_to, and auto_reply. stop_processing ends later rules. At most 20 rules (409 rule_limit). client_id returns the original rule. forward_to must be another inbox on this account or a verified owner (400 forward_target_not_allowed). A bad body is 400 invalid_rule. Write permission is message_update.

## Request

```json
{
  "name": "Archive newsletters",
  "conditions": {
    "list": true
  },
  "actions": {
    "folder": "archive"
  },
  "stop_processing": true
}
```

## Response

The OpenAPI document does not declare a JSON response schema for this call. The summary is the contract.

## Errors

- HTTP 409 rule_limit
- HTTP 400 forward_target_not_allowed
- HTTP 400 invalid_rule

The live `message` is the sentence for that code. Branch on `code`.

```json
{
  "error": {
    "type": "conflict",
    "code": "rule_limit",
    "docs_url": "https://cooperemail.com/docs#rule_limit"
  }
}
```

## Idempotency

client_id makes this write idempotent. Sending the same client_id again returns the original object instead of creating a duplicate.