# `UNKNOWN_FEEDBACK_PROVIDER` (HTTP 404): the bounce webhook path names an unsupported provider

The URL POST /api/v1/email/feedback/{provider}/{key} accepts postmark, ses, mailgun and sendgrid only.

Each provider path parses that provider's own webhook format and maps its events to delivered, bounced or complained. Any other name has no parser and is answered with this code.

**What to do.** Copy the exact webhook URL from the API keys page for your provider. For any other sending service, post normalized outcomes to POST /api/v1/email/feedback with your secret key instead.

```json
{
    "success": false,
    "error": {
        "code": "UNKNOWN_FEEDBACK_PROVIDER",
        "message": "Supported providers: postmark, ses, mailgun, sendgrid.",
        "request_id": "req_01m1kgdm4xngzmbmff68g94w0c"
    }
}
```

Reference: https://spaw.co/docs/errors/UNKNOWN_FEEDBACK_PROVIDER