When a customer places an order through Unimarket, suppliers are alerted via email. An email Purchase Order will look something like this. A PDF version of the PO will also be attached to the order within Unimarket.
If suppliers would like to view a history of orders in Unimarket, or flip those orders into invoices, simply log into Unimarket and choose View Orders from the Transactions section of the left hand hamburger menu.
Selecting an order number will allow you to view the order and invoice the order.
For more information on creating invoices in Unimarket, see How to Create an Invoice.