Managing multiple orders that contain an item that is not available can be time consuming. There is a feature that can address these orders simultaneously.
Navigate to Inventory/ Manage Inventory. Find or search for the item that is not is stock. Click on the item name. A new winodw will pop up dsplaying all the customers that have ordered the item.
If the item is out of stock, select item not available.
If you have limited stock you can allocate quantities to certain customers, add zero to other orders and write out of stock in the item comment
Click on the save button to close the pop up