Table name that stores email communication Purchase Orders

We are on 12.1.3 and our buyers communicate the aprpoved POs over to suppliers via email- Purchase Order Summary>Query the PO>Tools>Communicate>Email>enter the supplier's email address>OK.In some cases we have noticed that the suppliers do not get the email.Is there any table in Oracle that stores the information of such email communications that we can look at to see the status?WF_NOTIFICATIONS stores information only for workflow notifications and for emails if the workflow triggers one but in the case above this is a direct  email so this table does not have this information