If you use a Purchase Order from your Magento store for your clients, it's important to verify the PO and authenticate the customer.
Unfortunately, Magento does not have these features, so the Admin must manually handle these tasks before sending the order confirmation to the customer.
Fortunately, the Magento 2 Advanced Purchase Order module can simplify this process by allowing you to review the PO and validate the customer in one place.This Magento extension comes with:
Learn more about Advanced Purchase Order extension at https://www.navigatecommerce.com/magento-2-extensions/advanced-purchase-order-for-magento-2.html
Also, it is marketplace-approved: https://commercemarketplace.adobe.com/navigate-magento-2-advanced-purchase-order.html