On mobile devices, it appears in the center of the window.
You can customize the look and feel of the popup by changing all of the text elements or adding an image.
This image is optional.
Once a customer has submitted their email address using this form, it is added to your list of customers in the Customers area of your Shopify admin. Now, in order to send emails to your customers, you need to hook your customers up to a email platform via a Shopify app like ShopSync.