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

Auth: Bearer

HTML: https://cooperemail.com/docs/reference/inbox-notify

## Summary

Register a message.received webhook for this inbox. Body url is a public http or https address. Localhost, a private IP, and a name that resolves to one are rejected. The default client_id is notify:{inbox id}, so a second call updates the URL. The signing secret is returned on the first create and redacted after that. Deliveries use x-cooper-signature, x-cooper-signature-v2, x-cooper-timestamp, and x-cooper-delivery. A redirect is not followed. A trigger URL from Zapier, Make, or n8n can be the url. MCP: notify_url on cooper_create_inbox. The catalog has 67 tools.

## Request

```json
{
  "url": "https://example.com/hooks/cooper"
}
```

## Response

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

## Errors

The summary and the OpenAPI operation do not name an error code.

## Idempotency

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