modlet: Block PO Box & Lockers

Prevent return fees and failed deliveries instantly.

by modlet · Launched: March 2026 · Free plan available.

5.0 (1) on Shopify Built for Shopify

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Stop paying expensive carrier return fees for undeliverable addresses.

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About modlet: Block PO Box & Lockers

Protect your shipping margins with reliable, global PO Box blocking. Built natively into Shopify Checkout, it physically blocks checkout completion for restricted addresses—ensuring 100% reliability. Why offer a generous free tier? Built by a veteran cloud architect, our highly efficient infrastructure keeps costs low, and we love helping new stores get off the ground. Grow with us for free, and upgrade to Pro as your volume increases or when you need granular, custom shipping rules. Block PO Boxes and lockers worldwide to stop failed deliveries. Secure checkout blocking that buyers cannot bypass or work around. Test your blocking rules safely using the built-in address simulator. Pro: Create custom error messages to match your brand and local languages. Pro: Set specific exception rules for shipping methods, regions, or products. Show more Show less

Last verified: July 21, 2026 · Fresh

App details

Developer: modlet
Category: Marketing & conversion
Pricing: Free plan available
Launched: March 2026
Rating: 5.0 (1) on Shopify

Key features

Block PO Boxes globally (Instant setup)
Up to 250 Store Orders per Month
Native & Secure Checkout Validation
Address Simulator & Testing Tool
Unlimited Orders & Address Validations

Integrations with:

Checkout, Shopify Admin

3 plans · starts free · 14-day free trial

Free

Pro

$10.99/month

Enterprise

$99.99/month

Plans and prices as listed on the Shopify App Store.

Ratings & reviews

based on 1 Shopify App Store reviews

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Great app and excellent support. We installed Modlet PO Box Blocker because we needed a reliable way to block PO boxes, parcel lockers, pickup points, and similar addresses directly in Shopify checkout across international markets. During testing, we had a question around how the app handled some international address formats. The Modlet team was incredibly responsive, looked into it right away,...

— Pulse Mindfulness

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