-an update on this we applied the patch and it solved our issue
Some end-users open cases with the support claiming that they don’t receive all the email notifications related to some of their purchase orders, I thought that maybe their email were spelled wrong or maybe they changed their email preference so they don’t receive an emails at oracle application level like the last time, I checked both but none of the above applies on the case so I had to check an one of there POs on the wf_notifications table, I run the following query
select * from wf_notifications where subject like '%200700001052%'
and the email_status value was ERROR so I took the notification_id and search for it in the emails that were sent by the notification mailer to the sysadmin and I found an email with the following content
"Event Error Name: -20001Event Error Message: ORA-20001: Oracle error -20001: ORA-20001: APP-FND-02500: Error occurred during product initialization for MO when executing 'begin MO_GLOBAL.INIT; end;'.SQLCODE = -20001 SQLERROR = ORA-20001: APP-FND-02902: Multi-Org profile option is required. Please set either MO: Security Profile or MO: Operating Unit profile option.has been detected in FND_GLOBAL.INITIALIZE."
I check that error on metalink and I found 5 notes saying that I must apply patch (5209533) p5209533_11i_GENERIC.zip
I will apply that patch on my test/clone instance this weekend and I will update you if the issue was resolved.
For more info you can check note (393847.1) or search for the error/patch
Hope that helped