Coupa customers who only send the occasional purchase order to a supplier can use HTML-based email.
This is the simplest way to receive purchase orders and send invoices.
Coupa can purchase orders as an HTML-formatted email. The electronic copy of the PO includes all the information you'll need to fulfill the order. Additionally, Coupa can send orders to multiple email addresses. Provide your customer with at least one email address where they can send purchase orders.
Suppliers can send their PDF invoice to Coupa using the email address given to you by your customer. Unlike orders, invoices must be sent to a single email address.