Outlook: Adding a new Mailbox (iPhone) 1. Open Outlook App On your iPhone open the outlook app. Click your profile icon top left of the screen. 2. Add New Email Account As highlighted below, click the add email button. Then click add new shared mailbox. 3. Login in Enter in the email address of the shared mailbox.  4. Open the added Shared Mailbox You will need to navigate to the mailbox. click on your profile icon to open the main menu then choose the mailbox which you just added.