ConstReadonlyclientError: "clientError"Readonlyexpired: "expired"ReadonlyinvalidExpiresAt: "invalidExpiresAt"ReadonlyinvalidIdempotencyKey: "invalidIdempotencyKey"ReadonlymissingSigningKey: "missingSigningKey"ReadonlyrateLimited: "rateLimited"The third-party provider returned 429 (Too Many Requests). Callers should back off and retry.
ReadonlyrecipientCountAboveMaximum: "recipientCountAboveMaximum"ReadonlyrecipientCountBelowMinimum: "recipientCountBelowMinimum"Readonlyunknown: "unknown"
The third-party provider returned a non-429 4xx response. Retrying without changes is unlikely to succeed; fix the request or inspect the error before retrying.