Finding Hidden Mailboxes

Here's something that Nino Bilic from Microsoft recently came up with on the newsgroups, and I thought I'd share it with you here. It's the sort of thing that I easily forget how to do!

What's a quick way of finding all the hidden mailboxes that you may have on your system?

Hidden mailboxes are identified by the fact that the attribute msExchHideFromAddressLists is set to a value of TRUE. All we have to do is perform a custom LDAP query against our AD to search for users with the above attribute set accordingly.

This can easily be done with Active Directory Users & Computers:

1. Bring up Active Directory Users & Computers.
2. Right-click your domain name at the top, and choose Find.
3. In the Find combo box at the top, select Custom Search.
4. Click the Advanced tab.
5. Paste in the following LDAP query and then click Find Now.

(&(objectclass=user)(msExchHideFromAddressLists=TRUE))

The list of hidden mailboxes will then be displayed. Don't forget that this will include System Mailboxes. Be sure to leave those alone!