Each key can make 600 requests per minute. When you pass the limit, the API returns 429 with a Retry-After header.

Create a new key in Settings, deploy it, then revoke the old one. Both keys work until you revoke, so there is no downtime.

We retry with backoff for 72 hours. You can replay any failed delivery from the Events log after you fix the endpoint.

Every account has a sandbox with its own keys. Sandbox data resets on the first day of each month.