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Validation rules
Each rule decides what happens to a problem address: nothing, a warning after purchase, or a hard block at checkout. These pages explain what every rule catches and exactly what your buyer sees.
- PO Box addresses
This rule catches PO Box addresses before you buy a label for them. USPS delivers to PO Boxes. UPS, FedEx, and nearly every other carrier does not.
- Packstation and Postfiliale
For orders shipping within Germany, this rule catches DHL Packstation, Postfiliale, and Paketshop addresses. Only DHL can deliver to them.
- US military addresses
This rule catches APO, FPO, and DPO military mail addresses. Only USPS delivers to them, transit is slow, and tracking ends at the military mail facility.
- Missing house number
This rule catches street addresses that arrive without a house number. An order for “Main Street, Springfield” gives the driver nothing to deliver to.
- ZIP / postal code format
This rule catches ZIP and postal codes that don't match the destination country's format, like a four-digit ZIP on a US address.
- Unusual characters
This rule catches emoji and decorative symbols that break carrier label printers and sorting machines.
- Blocked countries
List the countries you don't ship to, and checkout stops those orders at the address form, before there's anything to refund.
- Blocked states and provinces
List the US states or Canadian provinces you don't ship to, and checkout stops those orders at the address form. This is also the only way to block US territories like Puerto Rico and Guam.
- Blocked ZIP / postal codes
List exact ZIP or postal codes you can't serve, and checkout blocks them on the spot. Useful for areas your carrier won't touch or surcharges heavily.