Using the system, you can adjust the payment you receive against the outstanding invoices. The customer can instantly view this update in his online ledger account. This saves your account department the hassles of digging out and furnishing details every time the customer enquires about the outstanding amounts. The same is always available to them at their end itself!
Since you can create a multi-user system at your end, your accountant can log in to any customer's ledger and update the payment received. Hence, your list of outstanding is always updated.