I wanted to allow other users full access to an email account “info”.  This is a generic account shared by a few users.  In SBS 2003, it was a simple click on the user in Active Directory, and edit a property.  In Small Business Server 2008 (or Exchange Server 2007) it’s a little more complicated…first go to the Exchange Management Console (Start – Programs – Exchange 2007).  Click on the EMC…then paste the following command into the free text console.
Add-MailboxPermission -Identity “Info” -User John -Accessright Fullaccess -InheritanceType all <ENTER>
Change the usernames as you like.  In the example above I am adding John to have rights to the Info account.  You can use the cursor keys to move back to allow you to edit the command.