The legitimate Out of Office is provided with a message subject of:
The second unwanted Out of Office is provided with a message subject of:
Out of Office
I created a test user account and send the problematic user a test email when her Out of Office was enable. The following screenshot shows the extra Out of Office message sent:
First thing I checked was the MailboxAutoReplyConfiguration set on the mailbox which shows the Out of Office message set on the Mailbox for both Internal and External recipients. This did not reveal the second Out of Office message causing the problem for this user account.
This means the second problematic Out of Office response must be stored elsewhere in the users mailbox. Before going gown the path of downloading MFCMAPI and manually browsing through the problematic mailbox for the second Out of Office rule, I decided to run the "outlook.exe /cleanrules" Outlook 2010 command. This command cleans and removes both server side and client side rules including any Out of Office rules which may exist in the mailbox.
Simply close Outlook on the users PC and then execute the following command:
Whilst a resolution to the issue was found, I am not sure what caused this issue. The problematic mailbox is a member of a Database Availability Group cluster and was migrated cross-forest from an Exchange 2007 environment. This should not cause problems as Exchange 2007 utilises a similar architecture for Out of Office messages as Exchange 2010 supporting the concept of both Internal and External Out of Office responses. I believe this mailbox has been around for a long time and this legacy rule may have been brought across from Exchange 2003 as this particular customer uses role based mailboxes and when new users come on-board they inherit the last users mailbox keeping the same email address.
Please leave your comments if you also experience this issue.