Hi Wakabayashi, I would like to share my experience regarding this. I have a Prestashop store and I am using the third party addon to handle return and refund request of the customers: https://addons.prestashop.com/en/customer-service/20146-knowband-order-return-managerreturn-slip-barcode.html. Prestashop return manager offers all features which help me to handle the customer return request and quite easy to use. With the help of this module, I am able to send the automated email to the customer. This extension worked pretty well for me. As per the feature, this module is cost effective.