Retention Tag not working on Outbox

Hi

We are running Exchange Server 2013 CU5 on Windows 2012 with Outlook 2010 SP2

We have configured Retention Policy and Retention Tags which are working on all folders - except the Outbox folder

I know email should not be stuck there but we need the tag to remove messages (which while in the Outbox they have been sent just not moved to the Sent Items folder)

When a message in that folder is opened, the Retention Policy information at the bottom of the message is missing

any ideas?

thanks

shapi