If customers are not logged in, a pop-up window will appear when they try to add

How to implement this feature?
If customers are not logged in, a pop-up window will appear when they try to add items to the cart, asking them to enter their email address.

Hi @kaiyang

This can be handled with our free extension to ShopMagic – Abandoned Carts. After activation, is settings, you will have an option to enable exit-popup for customers. It’s not entirely what you are asking for, but I hope this functionality covers your need.