Validate international addresses accounting for format variance, transliteration, and postal code rules

Verified steps

1. Use a global address validation provider (examples include Google Address Validation API, Loqate, Melissa Data, or carrier-native validation endpoints) that supports the destination country's address schema — do not apply US address validation logic globally.
2. For non-Latin script countries (Japan, China, South Korea, Arabic-speaking countries, Russia, etc.), accept addresses in either the native script or romanized (transliterated) form and pass both to the validator; confirm which form the carrier requires on the shipping label.
3. Validate postal code format against the destination country's rule (length, character type, and valid range vary widely — e.g., UK uses alphanumeric with a specific format, Canada uses alternating letter-digit, some countries have no postal codes at all).
4. Normalize address component order for label printing: many countries use the inverse of US order (largest to smallest administrative unit); ensure your label template renders in the correct local order.
5. For countries with high delivery-failure rates due to informal addressing (common in parts of Africa, Latin America, and Southeast Asia), consider augmenting with what3words or plus codes as a supplementary location signal.
6. After validation, store the standardized form returned by the validator rather than the user-entered form; re-validate on any address update before shipment.