The following is information on how to configure Outlook 2010 so that when someone sends an email as a shared mailbox, the email goes into sent items on the shared mailbox instead of the personal sent folder of the user who sent the email.
http://exchangeshare.wordpress.com/2009/07/15/shared-mailbox-added-in-outlook-profile-but-where-will-sent-item-be-saved/
Outlook 2010: See http://support.microsoft.com/default.aspx?scid=kb;en-US;2181579
Outlook 2003: Hotfix KB953803 needs to be installed for Outlook 2003 anthe registry key added in KB953804 to enable this functionality.
Outlook 2007: Microsoft has released an Outlook 2007 hotfix package dated June 30, 2009 to resolve certain issues and this issue is addressed in that list.
Install this hotfix package and add a registry key to make it enable.
1. Hotfix: Description of the Outlook 2007 hotfix package (Outlook.msp): June 30, 2009
2. Set below registry key as per KB972148 to enable this functionality.
[HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\Preferences]
"DelegateSentItemsStyle"=dword:00000001
