Issue: Out of Office is turned on for a user, but a Out of Office notification is not beingsent to internal/external users. You may see the Out of Office message internally BEFORE you send the message in the Outlook notification bar in the new message window.
Cause: Mailbox rules have corrupted or are conflicting with the Out-Of-Office rule in order to send a message to recipients.
Resolution: The resolution is to remove the conflicting rules in the mailbox. To do this:
1. From a run prompt use the following switch: outlook.exe /cleanrules .This will clean client and server rules for the mailbox. This is the fastest way of fixing this issue.
2. You can manually remove each rule in the mailbox.
Ex-Shell 