If you are using Outlook 2013, the mailbox for which you have been granted access automatically display in your folder list. In the example below, Adam Barr has been granted access to the mailbox of Kim Akers. Kim’s mailbox displays automatically in Adam’s folder list in Outlook 2013.
Note: If you were recently granted access to the mailbox, it may take a few hours for the other user’s mailbox to display in your folder list.