You create the mailbox as a resource. Once that has been done open the resource as its own profile (go to the control panel, switch to classic view or small icons, open the mail icon, click show profiles, set it to prompt you for a profile. Open outlook and when you get prompted click “new” and create a profile for the resource.) Open the resource profile, go to tools, options, click the calendar options button, then the resource scheduling button. You can set it there to automatically accept bookings and to automatically decline conflicts. Train users to invite this resource as a resource, not an attendee. If they invite it as an attendee someone has to manually accept the invite in the inbox. If they invite it as a resource it will autmoatically book or decline the meeting.