How to block specific customers from ordering on Shopify

Short answer: Prevent known fraudsters or serial returners from checking out by email, or by tagging their customer accounts. In Checkpost, choose “Block specific emails or addresses” from Templates, adjust the values, test it, then save and enable the rule.

The problem

Serial returners, chargeback abusers and banned resellers keep coming back. Cancelling their orders after payment costs fees and time.

How to set it up

1. Install Checkpost from the Shopify App Store.
2. Open Templates and choose Block specific emails or addresses.
3. Add emails, or tag customer accounts with "blocked".
4. Use Try this rule to test a sample cart, then click Save rule.

The rule

Checkout is blocked when any of these conditions are true:

• Customer has any of tags blocked
• Email address is any of [email protected]

Shoppers see: “We're unable to process this order. Please contact support.” at the top of checkout, once they reach checkout.

{
  "name": "Blocked customers",
  "match": "any",
  "conditions": [
    {
      "kind": "customer_tag",
      "op": "has_any",
      "tags": [
        "blocked"
      ]
    },
    {
      "kind": "text",
      "field": "email",
      "op": "equals_any",
      "values": [
        "[email protected]"
      ]
    }
  ],
  "message": "We're unable to process this order. Please contact support.",
  "target": "cart",
  "runOn": "checkout"
}

Where this rule works

These are cart and checkout validations, including supported accelerated checkouts. They are current-cart policies; they do not track previous purchases of a SKU. Shopify excludes POS, recurring subscription orders and native pre-order/Try Before You Buy flows from this API. See Shopify's validation compatibility.

Tips

• Tagging the customer account (blocked) is more robust than listing emails, and you can do it from the customer page.
• Use a neutral message: you don't need to explain why.

FAQ

What if they check out as a guest with a new email?

Email and tag rules only catch known identities. Combine with address or first-order rules for wider coverage.

Is this compliant with privacy rules?

Checkpost stores no customer data. It only checks the tag or email Shopify provides during checkout.

Related rules

Add block specific emails or addresses to your store