From the Neto dashboard, select Setup & tools > All Settings & tools.
Click on the Web Store tab and click Checkout Settings.
In the Checkout Settings section, tick Enable Out Of Stock Checkout.
This will change the Out Of Stock buttons on your website to Backorder, allowing customers to add items to their cart and make purchases.
Once enabled, you can view any orders that are currently on backorder, either by filtering from the Sales Order menu.