This is on a Win2k3 server with Exchange 2k3 and clients running Win XPusing the mail icon, any user can open another user folder in addition to his own via the "advance tab" and adding the user in the "open other user folder"Clients are using Office 2003,

Hi, I suggest you create two new mailboxes enabled user and check whether one user has permission to access the other users mailbox through Outlook. If the issue still persists, please locate the user by using ADUC. I would like to explain that the users are able to access others mailbox if they have one of following permissions: 1. On the Mailbox Right, the user has Full Access permission to others mailbox 2. On Security tab, the user has receive as permission of the mailbox Mike

will check into that, apparently all users have "domain admin"rights and the domain admins group has full access on the Exchange mailbox store.Its the only thnig I can think of other than the one metioned above.

Hi,Please understand that Administrator account, or member of Domain Admins/Enterprise Admins groups are explicitly denied access to all mailboxes other than your own. I suggest you refer to following article: How to assign service account access to all mailboxes in Exchange Server 2003 http://support.microsoft.com/kb/821897/en-us Mike