Oracle EBS Workflow Notifications are not reaching to outlook

Hi All,

I have customized sales order workflow to have approval functionality wherein an email will go to an authorized person with a PDF attachment which he/she will look and then approve or reject.

Everything was working fine a few months back but suddenly notification stopped receiving in outlook where the same can be seen from the application.

after doing a lot many brainstorming I noticed that this is happening because of the OAF region which is being embedded in the workflow notification for PDF attachments. in the wf_notification table, mail status is sent whereas in outlook no email is received for that particular notification id. other emails for same user is reaching to outlook ( other than having OAF region embedded).