Outlook | Adding a Shared Mailbox to Microsoft Outlook
This KB Article provides the steps to add a shared mailbox to Microsoft Outlook.
In Outlook, click File in the upper-left.
Click the Account Settings box, followed by the Account Settings... dropdown.
Click the Change... button.
Click the More Settings... button.
Click the Advanced tab.
Click the Add... button.
Enter the name of the shared mailbox, and click OK.
Click OK. (Outlook will become unresponsive for about a minute while it processes the change. Please be patient, as this is normal.)
At subsequent screens, click Next >, Finish, and Close.
By default, messages that are deleted from a Shared Mailbox in Outlook go to the Deleted Items folder of the person performing the action, not to the folder of the Shared Mailbox. Please see Outlook | Deleted Items from a Shared Mailbox for the steps to configure messages to go in the Deleted Items of the Shared Mailbox instead.