After connecting the mailbox, you can change its purpose from "Personal" to "Corporate" mailbox or vice versa .This setting can be changed in the properties of the box. Enter the "Mail" section on the top right of the page, click on "More", select the desired box and change its purpose. Changes Save.
"Corporate" can only be changed to the "Personal" account by the Account Administrator. If the "Personal" mail and the user has not enabled access to the Administrator, then there is no possibility to change the properties.
The manager in this case needs to go into the properties of the box and allow access to the Account Administrator for further switching to the "Corporate" mailbox.