WooCommerce - Waitlist v1.5.4

With WooCommerce Waitlist customers can register for email notifications when out-of-stock products become available. Keep customers happy with back-in-stock notifications. Notify people when a product is available. WooCommerce Waitlist lets you track demand for out-of-stock and backordered items, ensuring your customers feel informed, and therefore more likely to buy. Using this plugin, you can build a waiting list of people wanting the unavailable item, then notify customers automatically when products arrive.

DEMO:
https://woocommerce.com/products/woocommerce-waitlist/