All EU member states supported by VIES.
x-api-key and x-customer-email.
Each VAT number response is cached in S3 for 12 hours. On VIES outage we serve the cached entry and set source: "cache".
401 invalid_api_key, 401 missing_* , 403 access_denied, 403 plan_not_allowed, 429 rate_limit_exceeded.