Errors and limits

Errors use conventional HTTP status codes and a JSON body.

{
  "error": {
    "code": "invalid_recipient",
    "message": "The value of \"to\" is not a valid e-mail address.",
    "request_id": "req_4c7e0a12"
  }
}

Status	Meaning
`400`	The request is malformed or a field is invalid
`401`	Missing or revoked API key
`404`	The message or template does not exist
`409`	The action conflicts with the current state
`429`	Rate limit exceeded
`5xx`	Something went wrong on our side, safe to retry with an idempotency key

Rate limits

Live keys may send 100 requests per second. Responses include X-RateLimit-Limit, X-RateLimit-Remaining and X-RateLimit-Reset. When you receive 429, wait for Retry-After seconds before retrying.