Some recipients of internal sending of PO document doesn't receive any email notification about PO approval

Hi,

Have used SOST tcode to trace recipient of PO document for internal sending via Microsoft outlook. Have saw the recipients there.

But some of the recipients (sap users) of PO email have not received any notification that PO has been approved in Microsoft Outlook.

Just want to know the reason why it happened and the remedies for this issue.

Thanks and regards,

Jeremiah Dollente

MM Consultant