This is a boon for people who regular use a shared mailbox… Keeping track of the sent items in the “right place”, ie the sent items folder of the shared mailbox (rather than your own).
Check out the write up on this blog :
Essentially with a hotfix (from KB 972148) you can add the following registry key to get the sent items kept in the shared mailbox :
[HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\Preferences]
“DelegateSentItemsStyle”=dword:00000001