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Desk booking

Introduction to Desk Booking Using Microsoft Resource Mailboxes

Booking a meeting with colleagues and inviting a meeting room as part of that booking has been a well used – and robust – feature in Microsoft Outlook for many years.  It is now also available in Microsoft Teams.

The approach of booking workspaces and resources is made possible through using resource mailboxes.

What is a resource mailbox?

A resource mailbox is a Microsoft Exchange mailbox that can be associated with resources, such as meeting rooms and equipment.  Unlike a typical mailbox, it is disabled for sending or receiving emails, but it does have a calendar associated with it.

If the resource’s calendar indicates availability, the resource can be configured to auto-accept an invitation to a meeting.

You can also associate rules with the mailbox, for example, making accepting an ‘invitation’ subject to approval by a ‘delegate’ associated with that mailbox, such as a facilities manager.

Resource mailboxes can also have attributes, such as room capacity and location, which, when properly configured, can assist with selection of the resource.

Can I use resource mailboxes to book hot desks?


Until recently there were only two resource mailbox types:

  • Room mailboxes – ideal for representing available meeting rooms but they can also be used for other location-specific workspaces such as a demo suite or training room. 
  • Equipment mailboxes – ideal for representing ‘floating’ resources such as projectors and pool cars.  They are not typically associated with a given location and have fewer attributes.

Microsoft has now introduced a third type of resource mailbox that lends itself well to hybrid working spaces and hot desks.

Called workspace mailboxes, they are bookable resources that have an overall capacity associated with them.  This capacity is then enforced by Exchange by allowing multiple bookings for a workspace up to the maximum available.

For example, if you configured “Neighbourhood A” with a maximum capacity of 30, it would allow 30 separate bookings to be made, all managed by just one resource mailbox, rather than 30 individual ones. 

You can, of course, have a workspace that has a capacity of 1, which is ideal for hot desk booking.

Download our free eBook for the steps required to configure workspace resources in Microsoft 365.

The problems of using resource mailboxes to book hot desks in Microsoft 365

Although using resource mailboxes to represent and book desks is possible, you will find it falls short in the following areas:

1. It’s not easy for users to select their preferred desk

With the correct configuration you can give users a list of hot desks to select from according to location and attributes like ‘number of screens’ and ‘docking station’.

However, if you have anything other than a handful of hot desks, you may want something more useful than a list.

For example, interactive floor plans let users see at-a-glance where they’d like to sit:

  • Is it near to the coffee area?
  • Will it have a view out of the window?
  • Can I book a seat near my colleagues?

You can use Microsoft Power Apps to build an interactive floor plan that ‘layers’ on top of native Microsoft resource mailboxes, and we’ll write about this in an upcoming article.

2. Maintaining workspace resource mailboxes is challenging for FM professionals.

If you download our eBook, you will see that the steps involved in creating mailboxes and lists, adding attributes, involve working with PowerShell and the Exchange Admin Center.

This makes defining and maintaining available hot desks, meeting rooms, huddle spaces, etc., very much an IT function, and not one that can be easily managed by facilities staff. 

Even if the initial work of adding workspaces is carried out, there will be an ongoing maintenance overhead to reflect office re-organisations, decrease/increase in capacity, and so on.

3. You may need a lot more workspace & resource booking functionality

In addition to booking workspaces there may be other features and functionality you want, such as:

  • Automatically releasing workspaces in the event of a ‘no show’
  • Booking catering, additional equipment, visitor passes, and so on.
  • Digital signage to show free/busy status at a glance & on demand bookings
  • Workflows that update the AV, cleaning, catering, security teams, etc. on requests
  • Policies to govern who can book which resources when.  
    E.g., Giving certain departments priority for specific workspaces, make certain team spaces only available on a Monday or Friday
  • The ability for the FM team to move bookings (e.g., switch a meeting to a different room)
  • Capturing utilisation metrics to report on workspace occupancy and trends.

The list goes on.

4. Microsoft workspace booking is an evolving area

Microsoft is working hard in the whole area of connecting people in person and optimising workspace utilisation and developing the way resources are used and managed is part of this vision.

In fact, functionality was changing over the course of writing our eBook.  For example, one day, the Location picker in the Teams Calendar App listed workspace resources, the next day the workspaces we’d added were missing from the list!

STOP PRESS: In March 2024 Microsoft released a new Outlook ‘Hybrid’ RSVP feature that allows attendees to select if they’re joining virtually or in-person to a hybrid meeting. It’s yet to be released for Apple Mac and mobile users. Also, you can still be nebulous about whether you plan to attend in-person or virtually (by just responding with ‘Yes’), but it’s a step in the right direction.

It is not clear whether it will operate as intended with the ‘capacity counter’ associated with workspace resources.  You can read more about why Hybrid RSVPing is important in our earlier blog.

Although the RSVP issue is not related to a desk bookings per se, this constant change without warning means it’s difficult to build a system you can rely on.


Taking advantage of native resource mailboxes is undoubtedly a smart approach for Microsoft enterprises – especially larger ones.

As an approach it offers several advantages, including seamless integration with Outlook and Teams, multi-location scalability, automated security measures, prevention of double bookings, and much more.

Plus, you’ve already paid for it, right?

Out of the plethora of great-looking desk booking systems available on the market, there are a few that are able to take everything that is great about Microsoft resource mailboxes but fill in the gaps.

If you’re interested in exploring these solutions further and discovering how they can meet your specific needs, don’t hesitate to reach out to us for more information.

Find out how our workspace booking systems can build on your Microsoft 365 investment.