You need to make this change in AD U&C... Go to the help desk account and
open it up. Look for the Exchange Advanced tab. If you don't see it, go to
the View menu and select Advanced Features. Go back to the user account
that corresponds with the mailbox you want to be able to access. Click the
Exchange Advanced tab. Click the Mailbox Rights button.
Find or Add the User Account you want to be able to access the mailbox.
Give them
Full Mailbox Access Privileges. Apply, OK, Etc...
On the Machine that you want to access the mailbox from, log in with the
account you want to be able to open it with, open mail properties in control
panel. Select Microsoft Exchange Server, hit Properties, hit Advanced Tab.
You will see a section that says Open these additional Mailboxes. Click add
and add the account you want to be able to open.
OK... OK.... Etc...
Now Open Outlook and you should see two mailboxes, the one for the account
you are using, Administrator, and one for the account you just gave yourself
access to, helpdesk or whatever...
Hope this helps...
-Kevin Peck