To collect customer emails from your online store, add Email signup forms to your online store.
Email signup section in the Home page
Email signup section in the Password page
Once a customer submits the Email signup form, their email address will be collected and stored in your Customers section under the Shopify Admin panel.
Go to Shopify Admin > Customers and see a list of all the emails subscribed through the signup form.
Note: You can use your customers' emails to grow your business and build relationships with your customers. Sending newsletters to customers who sign up for your mailing list is a great way to let them know about new products and upcoming sales.