After you create the Exchange Mailbox client, must associate mailboxes with the subclient.
By default, you have the option to protect all mailboxes for all users except All O365 Group Mailboxes. This option is enabled when you assign Exchange policies to the All Users group. However, if you only want to protect mailboxes in specific databases or AD groups, do not assign Exchange policies to the All Users group.
This can be done by using the following: