Okay so if you’re an Exchange administrator or consultant working with pretty much any size of Exchange customers, you’ have probably been confronted with what I call the infamous “Sent Items” folder behavior that users see, when they have been delegated access to a mailbox.

More specifically, when a user has been delegated access to a mailbox (and maybe also “Send As” permissions) and opens the mailbox as an additional mailbox in his Outlook profile, he assumes that when replying to or forwarding messages on behalf of the additional mailbox, the emails go into the “Sent items” folder of the additional mailbox. However, this is not the case. Instead it goes into the “Sent items” folder of the primary mailbox in the Outlook profile.

The good thing is if the Outlook client runs in cached mode (yes cached mode is a requirement), this behavior can be changed using a client-side registry key.

The key works with the following client versions:

• Outlook 2010 SP1 (important to note that the hotfix isn’t included with RTM)
• Outlook 2007 (with hotfix: http://support.microsoft.com/default.aspx?scid=kb;...972148)
• Outlook 2003 (with hotfix: http://support.microsoft.com/default.aspx?scid=kb;...959628)

To change the behavior for items that leaves the additional mailbox, create the following registry key

Key: HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Preferences
Name: DelegateSentItemsStyle
Type: DWORD
Value: 1

Restart the client and you will now see messages in the additional mailbox that you either reply to or forward now goes into the “Sent items” folder of the additional mailbox.

Important
Those of you that have Outlook 2010 clients might be tempted to fix this behavior by creating additional accounts in the Outlook profile. But please bear in mind, when dealing with delegates, this is not a supported scenario. Read more here.

Until later,

Henrik Walther
Technology Architect/Writer/MS Vendor
MCM: Exchange Server | MVP: Exchange Architecture