This feature is available on our online store only. It is not available in our mobile app.
If a product is out of stock, you can enter your email address to be notified when it comes back in stock. When a product is out of stock you'll see a place to enter your email address and a "Notify Me" button.
Simply enter your email address and click "Notify Me". You'll be sent an email when the product is back in stock with a link to purchase the product.