Give an Administrator the Ability to Open and View the Contents of a User's Mailbox
Applies to: Office 365 for enterprises, Live@edu
Your organization may require that Exchange Online administrators be able to open another user's mailbox and view the contents, including reading e-mail messages.
By default, Exchange Online administrators or members of the Organization Management administrator role group can access a user's Options page in the Exchange Control Panel, but they can’t open the user’s mailbox and view the contents. You have to explicitly assign an administrator the permissions necessary to open another user's mailbox.
Assign permissions to one Exchange Online administrator
Run the following command:
Add-MailboxPermission <user's mailbox> -User admin -AccessRights FullAccess -InheritanceType All
Note You can also allow an ordinary user, such as an administrative assistant or human resources specialist, to open another user's mailbox by specifying that person in the User parameter.
Assign permissions to the Organization Management role group
Run the following command:
Add-MailboxPermission <user's mailbox> -User "Organization Management" -AccessRights FullAccess -InheritanceType All
Give full access to all user mailboxes in your organization
To give the Exchange Online administrator access to all user mailboxes in your organization, run the following command:
Get-Mailbox -ResultSize unlimited -Filter {(RecipientTypeDetails -eq 'UserMailbox') -and (Alias -ne 'Admin')} | Add-MailboxPermission -User admin -AccessRights fullaccess -InheritanceType all
To give members of the Organization Management role group access to all user mailboxes, set the User parameter to “Organization Management” in the previous command.
Open another user's mailbox
Here's how you open another user's mailbox after you've been assigned permissions: Open Another Mailbox.