Question : Administer Another User's Mailbox as Exchange Administrator

We have recently migrated from Exchange 2003 to Exchange 2007.  I need help understanding the best way to access other user's mailboxes as the Exchange Administrator.  Although I can add a profile for a user, when I try to set the out-of-office for someone in an emergency situation, I receive the message: Your Out of Office cannot be displayed because the server is unavailable.  When I try to access other users mailboxes from OWA,  (drop-down and Open ) it indicates I don't have permission.  In 2003 I could login as Exadmin, and change the URL address line to the to apppropriate mailbox name to open someone else's mailbox.  Often I'm asked as administrator to help with mailboxes of the general user community.  Can someone suggest the best approach for an administrator for these types of situations?

Thanks
C Emmons

Answer : Administer Another User's Mailbox as Exchange Administrator

Sorry for the delay. Its not wise from a security point of view to have an account configured with full access to all mailboxes the previous Exchange 2003 config you had was not following best practice.

However it can be done and I know what you mean re: Out of office setups etc been there myself. I did not test these but try the following commands.

You still need to use the shell : -

To add the permission to the mailbox store: -
Add-ADPermission Identity Mailbox Store User Admin User ExtendedRights Receive-As, Send-As

This should let you open the mailboxes: -
get-mailbox -resultsize:unlimited | set-mailboxpermission -user "Admin user" -accessright Fullaccess

You will need to run the second command regularly for new mailboxes.