Understanding bookings in Outlook

I’ve been seeing a surprising number of tickets from users asking why they are seeing double bookings of meeting rooms of late. In each and every case, the issue has boiled down to one of user error, with users not knowing or understanding how meeting invitations work in Outlook. This was a source of confusion to me, until a user put it as follows:

[…]However, when you add a room as a room, it also adds it as a person[…]

This indicated what they are misunderstanding, as well as how to best explain it to them. Here, then, is how I’ve ended up explaining it:

Meeting rooms are defined in Exchange, the server software to which Outlook connects, as resources, and are treated differently from other recipients. There are two ways to book a resource in Outlook. The way it should be done, which will avoid double bookings, is to send a meeting invitation from Outlook. Whether you use the “To”-field in the Appointment section, or in the Scheduling Assistant which lets you see what resources are available, the way it works is the same.

When making the invite from the Appointment section, you can click the “Rooms” button to the right of the Location field to choose the room or rooms needed. Please note that they will be added to both the Location and To fields, one denoting where the meeting is to take place, the other being the field that actually identifies the resource in Exchange.

That really is all you need to know. It can, however, be helpful to dig a bit deeper, and learn that Outlook sends invitations to three types of recipients; required attendees, optional attendees, and resources. Ordinary email addresses (i.e. any email address that hasn’t been defined as a resource) default to required attendance, while meeting rooms (and any other recipient defined as a resource) default to resource. You can also choose to add someone as an optional attendee (see screenshot to the left). If we move to the scheduling assistant, there are four different icons, denoting (from top to bottom, see screenshot below) the person inviting to the meeting, obligatory attendees, optional attendees, and resources (see screenshot to the right).

I initially said that there are two ways of booking a resource in Outlook. The correct one is shown above. The incorrect one is to add the booking in the calendar of the resource itself. The booking will not be rejected by the system, unless you don’t have permission to make the booking at all. This creates the only true double booking I’m aware of – though I will add that you cannot help but be aware of the fact that there is a double booking when you make the booking. There is, however, another perceived double booking, where the user adds the name of the meeting room to the Location field without using the Rooms button. The user may then believe that they have booked the room, though they have, in fact, not done so.