Customers do not receive gift card code

Hello,
We have enabled PW Gift Cards to our webshop. The product is displayed correctly, easily added to the basket and the purchase works fine. The system generates a gift card code. However no e-mail with the generated gift card code is sent to the customer, neither to the e-mail listed by the customer as receiver of the gift card. The customer can only see the code in the browser immediately after check-out. How can we ensure that the 16 digit gift card code is sent via e-mail to the customer or the e-mail listed by the customer as receiver?
Thank you in advance for your support