With YITH Multi Vendor you can turn your e-commerce store into a marketplace (a multi-vendor platform) like Amazon or Etsy. Turn your e-commerce store into a marketplace (a multi-vendor platform) and earn commissions on orders generated by your vendors.
When used with YITH Waitlist, also your vendors will be able to get email lists for their out-of-stock products and inform their potential customers when the item is back in stock.
To use this feature, make sure you install and activate both plugins. Then, select Manage waiting lists for their products in the option Regarding his/her orders, a vendor can, available in YITH > Multi Vendor > Vendors > Vendors permissions.
Now, whenever a product is out of stock, the user will be able to see a box on the product page to enter their email (or a checkbox if already logged in) to subscribe to the waitlist for that product.
Also, vendors will be able to see a Waiting List menu in their dashboard and check all products that have an active waiting list and the users in it, send emails, delete users and so on.
For information about setting up the YITH WooCommerce Multi Vendor plugin, please take a look at the documentation.