Checkout Address Guard
Still dealing with PO Box returns? Block them at checkout — before they cost you another shipment, another support ticket, another lost sale.
- Detects 50+ PO Box patterns automatically — 100% server-side blocking before payment
- Works with Shop Pay, Apple Pay, Google Pay, and PayPal Express out of the box
- Built-in simulator and allowlist to verify everything before you go live. No theme edits, no code
Why this matters
Every PO Box order that slips through costs you $10–$30 in reshipment fees, plus the support time to fix it. Multiply that across a month and the numbers add up fast. Checkout Address Guard catches PO Box addresses server-side at checkout and stops them before payment goes through.
Returns on repeat
UPS, FedEx, and DHL cannot deliver to PO Boxes. Every undeliverable shipment means return processing, reshipment costs, and margin lost — month after month.
Support buried in address fixes
"Could you update your shipping address?" — every one of those emails costs your team time and your customers patience.
Cancellations and rating damage
Shipping delays turn into cancellations and refund requests. Worse, the negative reviews that follow keep hurting your store long after the order is gone.
Best suited for
- D2C brands using FedEx or UPS as their primary carrier, dealing with recurring PO Box returns
- B2B merchants shipping medical devices, precision parts, or high-value equipment where a single return is costly
- Operations teams managing multiple carriers, warehouses, or cross-border shipping where address errors are hard to catch
Key features
50+ patterns detected automatically
P.O. Box, PO Box, Post Box, P O Box — no matter how customers type it, it won't slip through. Scans address1, address2, and company fields with auto-normalization. Not a warning — a full stop before payment.
Custom patterns
Your store, your rules. Add custom block keywords from the admin — no code required. When a new edge case appears, you can handle it in seconds.
Allowlist
Never block a legitimate address. The allowlist is evaluated before any block rule, so trusted addresses — partners, repeat buyers, known locations — always pass through.
Custom error message
Tailor the blocked-address message to match your brand voice. Tell customers exactly what to do next. A sensible default is included out of the box.
Test simulator
Sleep easy before go-live. Enter any address in the admin to see BLOCK or PASS in real time. The simulator shows match reason and rule type so you catch config mistakes before your customers do.
One-click ON/OFF
Running a flash sale or handling an edge case? Disable blocking instantly with one click. Re-enable and it takes effect immediately. Stay in control without disrupting operations.
Getting started
Install
One click from the Shopify App Store. No theme edits, no code changes — nothing to break.
Activate
Turn on Enable in the admin and activate the checkout rule. You'll be done in about 5 minutes.
Test and go live
Verify with the built-in simulator, then publish. PO Box orders are blocked before payment from that moment on.
FAQ
Security & data handling
- Address data
- Processed in real-time at checkout only. Never stored, logged, or transmitted externally. Discarded immediately after validation.
- Data stored
- Shopify OAuth session (for authentication) only. Automatically deleted when the App is uninstalled.
- Data not stored
- Customer names, emails, phone numbers, order details, payment information, browsing history, IP addresses
- API scope
- read_validations only. No access to customer data, order data, or any other sensitive scope.
- Cookies and tracking
- None. No cookies, pixel tags, analytics SDKs, or browser fingerprinting of any kind.
- Third-party sharing
- None. No data is sent to any service outside Shopify, except as required by law.
- Communication
- All traffic over HTTPS (TLS). Webhooks verified via HMAC-SHA256.
- Compliance
- GDPR and CCPA/CPRA compliant. All Shopify mandatory webhooks implemented (customers/data_request, customers/redact, shop/redact).
Get started with Checkout Address Guard
Install from the Shopify App Store and start right away.