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Use Cases

Block PO Box Addresses at Checkout for UPS, FedEx & Startrack

Carriers like UPS, FedEx, and Startrack cannot deliver to PO Boxes—merchants discover this the hard way when packages are returned or undeliverable. Many assume enabling PO Box blocking covers every variation, but edge cases regularly slip through: addresses like "Box 20432", "HC Box", "Locked Bag", and parcel locker formats. Address Ninja blocks these variations at checkout so only deliverable addresses make it through.

Below we cover what po box blocking means for Shopify merchants, how Address Ninja handles the setup, and links to setup guides and detailed articles.

Address Validation vs. Address Verification: Address validation checks that an address meets format and business rules: house number present, postal code in the correct format, no PO Box, no blocked characters or restricted postal codes. It does not check whether the address actually exists. Address verification (sometimes called address autocomplete or address lookup) uses external services like USPS, Google, or Loqate to confirm that a street, city, and postal code combination is real and deliverable. Address Ninja performs validation — it enforces your rules at checkout — but it does not perform verification. If you need to confirm that an address exists, you'll need a separate verification or autocomplete service.

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Install Address Ninja on Shopify and see the difference today.

Install Address Ninja on Shopify