Email Notification sent to the Requisitioner when PO is emailed to Supplier

The last step in the Purchase Order approval process is an approval from the Purchasing Manager.  The buyers create the PO, then the PO is submitted to the Purchasing Manager as the final step.  Once the Purchasing Manager approves the PO, a .pdf of the PO is emailed to the supplier.  At the same time the PO is sent to the supplier, we would like a notification with the attachment also sent to the Requisitioner.