modlet: Block PO Box & Lockers

Pricing: Free plan available. Free trial available.
Rating: 0.0 (0 Reviews)
Developer: modlet

View demo store

Screenshot of checkout with error message displayed under PO Box

Prevent failed deliveries and carrier return fees by blocking PO Boxes at checkout.

Shipping carriers like UPS and FedEx cannot deliver to PO Boxes, leading to expensive return fees and frustrated customers. This app runs natively on Shopify Functions to instantly block undeliverable addresses at checkout. Our app uses advanced pattern detection to catch worldwide variations of PO Boxes, Lockers, and Military Addresses. Whether you are optimizing your standard fulfillment or enforcing strict shipping rules for regulated goods, our basic tier gets you started in seconds.

Block PO Boxes, Lockers, and Military Addresses to prevent failed deliveries.
Stop expensive UPS/FedEx carrier return fees instantly.
Native Shopify Checkout integration—unhackable with zero theme code.
Exempt specific countries or shipping methods from blocking rules.
Perfect for general logistics or strictly regulated shipping requirements.

Languages

English

Works with

Checkout

Pricing

Free

Features

Block PO Boxes globally (Instant setup)
Unlimited address validations
Native Shopify Function (<5ms latency)
Address Simulator & testing tool
No theme code or JavaScript required

Pro

$10.99 / month

or $99.90/year and save 24%

Features

Granular Pattern Rules
Shipping Method Exemptions
Country & Region Whitelisting
Product & Collection Exemptions
VIP Customer Tag Exemptions
Cart Condition Logic
Custom Error Messages

14-day free trial

All charges are billed in USD. Recurring and usage-based charges are billed every 30 days.

Reviews

Overall rating

Counts per rating level

0% of ratings are 5 stars
0% of ratings are 4 stars
0% of ratings are 3 stars
0% of ratings are 2 stars
0% of ratings are 1 stars

All reviews

No reviews yet

Support

App support provided by modlet.

Resources

FAQ

Developer

modlet

4370 Chicago Drive SW, Unit #744, Grandville, MI, 49418, US

Launched

March 9, 2026

Data access

This app needs access to the following data to work on your store. Learn why in the developer's privacy policy .

View personal data:

Customers, store owner

Customers

Name, email address, phone number, physical address, geolocation, IP address, browser and operating system
Store owner

Name, email address, phone number, physical address

View and edit store data:

Products, orders, Shopify Functions, Online Store

Edit products

Products, collections
View orders

Shipping information
Edit Shopify Functions

Delivery customizations, cart and checkout validations, cart transforms
Edit Online Store

Metaobjects
View other data

Shopify Markets settings