Shopify's "once per customer" limit only checks the email, so the same shopper can claim your first-order discount again with a new address or a Gmail alias. RepeatStop recognizes them by normalized email, phone and shipping address. At checkout it rejects the welcome code for buyers who have ordered before. Orders that slip through are tagged, explained and held for your review before anything ships. A 60-day audit shows how much welcome discount repeat buyers have already claimed.

• 60-day audit: how much first-order discount went to repeat buyers
• Rejects welcome codes at checkout for buyers who have ordered before
• Sees through Gmail dots and +aliases, phone formats and address spellings
• Holds suspicious orders for review, with a clear reason on every flag
• Blocklist problem customers; exempt wholesale, staff or B2B tags