Managing millions of tasks, Todoist is an online task management app and todo list. It has Web, iPhone, Android, Chrome, Firefox, Outlook flavors (and more!).
Create an assigned follow-up for each unapproved bill due soon.
Get clear follow-up tasks for bills nearing payment, so your payables person knows which approvals to chase.
Note received-versus-invoiced gaps on supplier bills.
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.