Reminder to requester after need by date expired (RQ - PO)

Summary:

How to send a reminder to the requester of a purchase order line that has not been received after the due date

Content (required):

I can enable a reminder that notifies by mail a purchase order program without receiving after the expiration date of the due date; and that this is not to the buyer but to the applicant of the line since the PO was created following an RQ? 

Version (include the version you are using, if applicable):

23B

Code Snippet (add any code snippets that support your topic, if applicable):