Setup Exchange 2010 Full Access Permissions

To give a user full access to another users mailbox in Exchange 2010, follow these steps:
Open the Exchange Management Console





Click Yes on the User Account Control Dialog if it appears





On the left hand side of the screen, navigate to Microsoft Exchange –> Microsoft Exchange On-Premises –> Recipient Configuration


Select Mailbox





Right Click on the user’s mailbox you wish to give access to, and select Manage Full Access Permission…





Click Add…





Select the Name of the user you wish to give access to, and click OK





Click Manage





Click Finish






You can also accomplish this by using Powershell.  In this example, Andrew will be given full access to Craig’s mailbox:


Add-MailboxPermission -Identity Craig -User Andrew -AccessRights FullAccess


You can also use groups.  In the example below, the group called Sales Users will be given full access to Craig's mailbox:


Add-MailboxPermission -Identity Craig -User "Sales Users" -AccessRights FullAccess


To do bulk changes, you can follow the post here (new window):  http://anonit.blogspot.com.au/2014/07/changing-exchange-2010-mailbox.html