Auto-mapping shared mailboxes in Exchange 2010 SP1 with Outlook 2010 and Outlook 2007

If you've read the Exchange Team Blog's announcement for SP1 you may have noticed one of the new features mentioned that isn't so widely publicised:

"On the client side features like auto mapping of shared mailboxes to user’s Outlook 2010 profiles will remove a support headache."

As it's one of my favourite new features and there's not much documentation yet, I wanted to write a little more about the feature and demonstrate how it works in practice…

How it works

When you add full mailbox permissions on Exchange 2010 SP1 to a new or existing shared mailbox that's also on SP1, Exchange now updates an Active Directory attribute on the shared mailbox itself, named msExchDelegateListLink. This is a multi-value attribute containing a list of DNs (Distinguished Names) of the other mailboxes that have full access to the mailbox and should auto-map that mailbox:

The next time Outlook 2010 or Outlook 2007 launches they searches for mailboxes that have the user's mailbox DN listed and displays them below the user's primary mailbox.

In previous versions this was accomplished by going to the user's Exchange accounts settings, going to "More Settings", choosing "Advanced" and entering the shared mailbox manually under "Open these additional mailboxes" as shown below.

For any organisation making use of a large number of shared mailboxes this is a bit of a pain as IT needs to both write documentation so users can do this themselves and in many cases do it for the user. The new feature simply removes this step.

The catch (!) is that just moving a shared mailbox to SP1 or upgrading isn't enough to enable the feature. As it's an extra attribute added at the same time as the permissions, you need to remove and re-add the permissions via the normal way (EMC or Powershell's Remove-MailboxPermission/Add-MailboxPermission) to make this take effect, or do it yourself via ADSI scripting/AD Powershell (probably not very supported!).

Demonstration

Just to give you a quick demo of how simple this is, all you need to do is add permissions on the Shared Mailbox in the normal way:

Then on the client, close and open Outlook. The Shared Mailbox should show after a few seconds:

Yes, it's really that simple. Simple enough that you might use it without even noticing and wonder how that shared mailbox got mapped in the first place.. But I think it's definitely going to be a feature any IT department that routinely adds/removes permissions for mailboxes this way will appreciate.

Disabling the feature selectively

I’ve had a lot of comments from people who don’t want this to happen all the time. If this is you, the check out my other article Disable Exchange 2010 SP1′s Auto Shared Mailbox Mapping Feature.