Approval Mails fail when sending to Approver for PR/PO's
Created purchase requisition, and forwarded to supervisor, supervisor is not receiving the email for approve requisition,however notifications are going in oracle to supervisor.for the same when I checked in wf_notifications mail status is showing as 'FAILED', this is happening for some Purchase requisitions/ Purchase orders.
Can some one please help me to how can I find the root cause for this issue ?