The mailbox should appear beneath your Inbox in the Outlook client. Once you find the desired mailbox, click OK, Apply, and Ok again. In the 'Add Mailbox' dialog box, enter the name of the Shared Mailbox or enter a unique word that is part of the Shared mailbox name to help you limit the search, but help you find the mailbox you're looking for.Make sure the shared account is not set to be hidden from the Exchange address book at this point. Give a licensed account full access permissions to the shared mailbox. As a workaround you can use the “Rules and Alerts” feature of Outlook to send an auto reply: 1.