Do all the artwork files uploaded by my customers need to be print-ready?

It is your responsibility to ensure all files pushed to 4over are print-ready. You can set the Preflighting tool available in the storefront to allow your customers to Preflight and approve the order prior to checkout or you can set the Preflighting tool to be available in the admin only to be approved by the storefront administrator.

* Even if the customer approves their order in the Preflight tool you should check the files to make sure they are correct when reviewing in the admin