How to Block a Customer on Shopify (And Why You Might Need To)

When Fraud Detection Isn't the Right Tool

CustomerGenius was built to catch discount fraud — customers who create multiple email accounts to exploit first-time discounts. That's still the core use case.

But merchants kept asking us for something different: a way to permanently block a specific customer, no discount code involved. Not because they were gaming a promo, but because they were someone the merchant simply didn't want to do business with anymore.

A customer who was verbally abusive to your support staff. A competitor placing test orders to monitor your pricing. A serial returner who's placed and refunded six orders. Someone you've already refunded once for fraud, and they've come back with a new email address.

The blocklist feature handles all of these.

How It Works

It's designed to be as simple as possible. When you identify a customer you want to block:

1. Open their customer profile in Shopify Admin

2. Add the tag cg_blocklist to their account

3. That's it

From that point on, CustomerGenius monitors every new incoming order and checks whether it's associated with that customer — even if they've created a new email address, changed their phone number, or modified their shipping address.

The same multi-signal matching that powers our discount fraud detection is working here: email, phone number, billing address, shipping address, and customer name are all compared against the blocklisted profile. When enough signals match, the order is automatically cancelled and refunded before it fulfills.

Why "Just Block the Email" Isn't Enough

Shopify doesn't have a native customer blocking feature. The workaround most merchants use is blacklisting an email address — but this only stops orders placed with that exact email.

A determined customer who knows they've been flagged will simply create a new account. They already know your products, your checkout flow, and what information they need to provide. Switching to a new email takes thirty seconds.

The cg_blocklist tag works differently. It ties the block to the customer's identity across multiple signals, not just one identifier. A new email address doesn't reset the block.

Common Use Cases

Abusive customers. If a customer has been hostile to your team — repeated threatening messages, harassment, aggressive demands — you're under no obligation to continue serving them. Add the tag, and any future orders they attempt will be automatically cancelled.

Competitors. It's common for competitors to place orders to monitor your pricing, packaging, and product quality. If you've identified a competitor placing test orders, blocklisting them prevents future orders from reaching fulfillment.

Chronic chargebacks. Some customers place orders and then file chargebacks as a matter of habit. Blocklisting them after the first incident prevents repeat exposure to chargeback fees and lost inventory.

Known bad actors. If a customer was caught abusing a discount code, refunded, and has now returned under a new email address, the cg_blocklist tag lets you act on what you already know about them — not just what their new email address tells you.

What Happens to the Customer

When a blocklisted customer places an order, CustomerGenius issues a full refund via the Shopify API. Depending on your notification settings, both you and the customer can receive an email alert.

The customer receives their money back. The order does not fulfill. No products are shipped, no inventory is allocated, no fulfillment service picks the order.

The Difference Between Blocklist and Fraud Detection

The fraud detection feature is code-based: it monitors orders placed using specific discount codes and scores them for abuse signals. The blocklist feature is customer-based: it monitors a specific individual regardless of what discount code, if any, they use.

They're complementary. Fraud detection catches unknown bad actors by pattern. The blocklist handles known bad actors by identity.

Most merchants use fraud detection as their primary protection layer and the blocklist as a manual escalation tool for cases that require a harder response.

How to Add the Tag

In Shopify Admin, navigate to Customers, open the customer's profile, and add cg_blocklist in the Tags field. Save the profile. CustomerGenius picks it up automatically — no additional configuration required.

The tag can be removed at any time if you decide to unblock a customer.