If the package was marked as delivered by the carrier, but the customer reports they have yet to receive it, Printful won't cover the cost of reshipping or refunding the order.
There may be cases where the delivery was made, but the package was left in an unexpected location at the customer's address. Customers should reach out to the carrier and inquire if any additional details were left by the delivery person. For example: “Left under the table on the back porch."
If your customer is unable to locate the package, you will need to place a new manual order to have it reshipped. We're not yet able to assist with filing claims with shipping carriers but hope to do so in the future!