Outlook Desktop - How to open a different mailbox

Delegate access

To be able to access a different mailbox the owner of that mailbox has to give you permission.

When Outlook is open, go to File

Under the Info tab press Account Settings - Delegate Access

Press Add, select the user that needs access to the mailbox.

After adding the user you'll need to choose the permissions.

When the person is added, do not forget to check the Deliver meeting requests option.

Press OK.

Add mailbox

Now that you have the permission to access the owners mailbox you can add it.

When Outlook is open, go to File

Under the Info tab press Account Settings - Account Settings...

Double click on your e-mail address

Got to More Settings

Click on the Advanced tab and Add the mailbox by typing the mailbox owner name.

You've successfully added a mailbox!