Answer
New-customer codes are normally limited to a first qualifying purchase or account, while existing-customer promotions are designed for returning shoppers. Retailers decide how they identify eligibility.
Using a different email address does not necessarily make an order eligible. Retailers may use account history, delivery details or other conditions, so check the published terms before relying on a first-order code.
What to check before checkout
Read the retailer’s current promotion terms, confirm that the code applies to the items in your basket, and make sure the expected saving appears before you pay.