Failed Mail Status On Workflow Notifications in oracle r12 apps

Recently we faced this issue,

PO Approval mails, workflow notification mails not receiving on users mail id, getting notification on oracle applications login, but no error notified on workflow status.

Workflow notification table "wf_notifications" workflow status open but if we check the mail_status failed,but before it was working fine.

Found solution on oracle support "

Getting A Failed Mail Status On Workflow Notifications For Purchase Order Emails to Suppliers (Doc ID 1101820.1)

Notification_preference for recipients become DISABLED in FND_USER_PREFERENCES and WF_LOCAL_ROLES and wf_users tables.

Cause:

Due to mail server crash for serveral hours the recipeints notification preference to change disable in fnd_user_preferences and wf_local_roles tables.

select user_name from fnd_user_preferences where PREFERENCE_VALUE = 'DISABLED';

Solution:

To resolve this issue need to manually change notification preference options for paritcular recipient in fnd_user_preferences table.

Disabled user login into oracle application (OAF)  > home page screen top right corner click "preference" options>

on bottom notification preference column change the disabled to "plain txt with HTML attachments". >then apply.

After rerun "sync roles conncurent program" Issue will be resolved.

To test use workflow "TEST MAILER" options in oracle application.