iSupplier Portal Invoice Notification

We are about to deploy iSupplier Portal and were curious as to how other users were deailing with Invoice notifications.  Specifically, how does the Buying Company know when an Invoice has been created and submitted by a Supplier?  How does the Buying Company personnel know to look for Invoices that have been sent to them by Suppliers?  What information on the iSupplier-generated Invoices is used to communicate to the Buying Company and its personnel that there are Invoices waiting for them to process?  I don't see anything built into the product that does this automatically. We are pursuing developing Oracle Alerts