userRateLimitExceeded — User Rate Limit Exceeded

The Gmail user has sent or read too many requests in a short time. Riposte surfaces this 403 error when an account hits a per-user quota. Implement backoff: pause or slow down requests for this user. For example, you can temporarily pause the account's sync via /accounts/{accountId}/pause and resume later. Distributing work across multiple accounts or reducing frequency will help avoid this limit.