Google Contacts, the address book built into Gmail, lets you keep track of all your contacts, see when you last interacted with them, and more.
Mark missing receipts on bill tasks before their due dates.
Your payables lead sees missing receipts before bills come due, with the next owner named on the bill task.
Mark bill tasks when invoiced quantities exceed receipts.
Your bill reviewer sees the quantity gap or missing receipt ID on the task, so they can decide what to do with the supplier bill.