To acknowledge receiving a successful webhook call, your endpoint should return a 2xx HTTP status code. All response codes outside this range, including 3xx codes, will indicate to us that you did not receive the webhook call.
This does mean that a URL redirection or a "Not Modified" response will be treated as a failure. we will ignore any other information returned in the request headers or request body.
We will attempt to deliver your webhook calls for up to two 4 hours with an exponential back-off. Webhooks cannot be manually retried after this time.