An Inbox can be made available to specific User Groups instead of public. Unselect the Public check box in the record view for the Inbox, then, navigate to the User Groups tab and select the user group(s) that can use the Inbox.
An Inbox can be made available to specific User Groups instead of public. Unselect the Public check box in the record view for the Inbox, then, navigate to the User Groups tab and select the user group(s) that can use the Inbox.