When I sent a message on behalf of someone via Exchange, that message is placed in my Sent Items folder and not in the Sent Items folder of the second mailbox.

How can I configure this?

Support for saving Sent Items in the owner’s mailbox depend on your version of Outlook and how the additional Exchange account has been added to Outlook.

For Outlook 2003, Outlook 2007 and Outlook 2010, you’ll need to install a Hotfix or the latest updates to control the Sent Items for Delegate mailboxes via the Registry. Outlook 2013 provides support for this out of the box.

When you are connecting to Exchange 2010 SP2 RU4 or later, then you can also configure this in OWA. It then works on every computer that you use without needing to set the Registry key for Outlook.

In addition, Outlook 2010 and Outlook 2013 also allows you to add multiple Exchange accounts to support this without the need to apply a Registry change.

Hotfix for Outlook 2003, Outlook 2007 and Outlook 2010

Support for “saving a sent item in the mailbox of the owner when sending it as a delegate” was first introduced in Outlook 2003 as a post SP3 Hotfix and also been made available for Outlook 2007 in a post SP2 Hotfix. Initial support for this was broken in Outlook 2010 and then bugged before it got fixed completely in a pre SP1 Hotfix.

Download: Outlook 2003 – Hotfix KB953803
Download: Outlook 2007 – Hotfix KB970944
Download: Outlook 2010 – Hotfix KB2547227

Note: The above hotfix might not be required when you already have a later rollup update or Service Pack installed.

DelegateSentItemsStyle Registry key

Once you have installed that Hotfix (or a later rollup update or Service Pack), you’ll have to add the DelegateSentItemsStyle value in your Registry.

Key location for Outlook 2013:
HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\Preferences
Key location for Outlook 2010:
HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Preferences
Key location for Outlook 2007:
HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\Preferences
Key location for Outlook 2003:
HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\Preferences

Value name: DelegateSentItemsStyle
Value Type: REG_DWORD
Value: 1

When the value is set to 0 or the value name is missing, the Sent Items will be stored in your own