Address rule simulator
Test any address in a simulator before you publish the rule — then roll back in one click if needed
PO Box Blocker — AddressFence (Shopify App Store). Free blocks PO Boxes and parcel lockers on the shipping address at checkout, plus a small set of ZIP rules. Street-number checks and billing-address rules are on a paid plan. Test any address in the simulator before publishing, with one-click rollback.
Related: B2B PO Guard — Require PO — B2B purchase order number required at company checkout.
Free check first: PO box and street number address checker runs in your browser and sends nothing. Paste addresses and see which look like a PO box or lack a street number.
Publishing without a simulator is a different risk than shipping-only native rules
Checkout Blocks address format validation can block PO boxes on shipping and has been available to all merchants since the 17 June 2026 changelog. Shopify Help states it cannot target billing. Before you turn on a billing PO box or street-number rule, run sample addresses through a simulator so you see the block or pass result, then publish — and keep one-click rollback if a real checkout surprises you.
Install PO Box Blocker — AddressFence
How to simulate, then publish
- Draft the billing PO box and/or street-number rule you intend to enforce.
- Test sample addresses in the simulator (pass and fail cases) before publish.
- Publish the rule for live checkout. Shipping PO Box and parcel-locker rules publish on Free; billing-address and street-number rules need a paid plan.
- Use one-click rollback if you need to reverse the publish quickly.
Install PO Box Blocker — AddressFence
Not the same as billing-block how-to, street-number sunset, or billing-match
- Block PO Box on billing — why billing needs its own rule. See PO box blocker for the billing address.
- Require street number after Address Blocker sunset — shipping street-number gap. See require street number at checkout.
- Billing match ≠ PO Box block — a different checkout setting. See billing match is not a PO Box block.
- Rate hide vs checkout validation — shipping-rate tricks. See rate hide vs checkout validation.
Install PO Box Blocker — AddressFence
What this page is not
- Not a claim that native Checkout Blocks can target billing addresses.
- Not a substitute for the billing-block, street-number, or billing-match siblings.
- Not legal advice about which addresses you must refuse.
Install PO Box Blocker — AddressFence
Related pages
- PO box blocker for the billing address
- Require a street number at checkout
- PO box blocker apps: billing vs shipping
- PO box spellings and look-alike street names: test your Shopify billing rule first
- PO Box Blocker — AddressFence
Test sample addresses in the simulator before you treat a publish as final. Native Checkout Blocks can block a shipping PO box; the simulator is for billing PO box and street-number rules. Sources: Shopify Changelog · Help: address format validation · AddressFence on the App Store.