This guide provides steps to add an Exchange mailbox to Outlook 2013. It instructs users to open Outlook 2013, go to the Account Settings, click on the Advanced tab, and click Add to enter the email address of the delegated mailbox. This may take a few minutes as Outlook accesses the other mailbox's database. Once complete, both mailboxes will be accessible in the Outlook profile. The document also mentions an Exchange recovery software that can help add mailboxes to Outlook if the manual method does not work.