POST to the addresses validate endpoint (verify current path in docs) with an array containing one or more address objects; each object should include 'name', 'address_line1', 'city_locality', 'state_province', 'postal_code', and 'country_code'.
Inspect the response array; each result contains 'status' ('verified', 'warning', or 'error'), 'original_address', 'normalized_address' (if validation succeeded), and 'messages' array with specific issue codes and descriptions.
For 'verified' results, use 'normalized_address' in your label purchase payload to ensure standardized formatting accepted by the carrier.
For 'warning' status, review the 'messages' to determine if the warning is acceptable (e.g., a suite number was standardized) or requires user correction before shipping.
For 'error' status, surface the specific 'messages' to the user for correction and block label purchase until the address is valid.
Known gotchas
ShipEngine address validation uses USPS data for US addresses; international address validation accuracy varies by country and should be treated as advisory.
A 'verified' result means the address is recognized in postal databases but does not guarantee the recipient is at that address or that delivery will succeed.
Batch validation accepts multiple addresses in a single request (verify maximum batch size in current docs); use batching for high-volume address imports to reduce API calls.
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