reading the Username of outlook

I have an exchangeserver with multiple outlookclients.
And i need to read whos profile the outlook client on a machine is currently
using.

I have tried to read the mapi.folders and can see a name called "Mailbox -
Alan Hebo Jensen", but i have added some other mailboxes , so i can also see
them.
Is there anywhere i can see that the first mailbox is the usermailbox , or
can outlook tell me who is using outlook.

Alan Hebo Jensen