Prevent Double-Bookings in Office 365 Calendar

We keep getting Office 365 sites coming the blog with search terms something like "prevent double bookings in 365 calendar."  

Invariably they find our post Double-Booked Meeting Rooms in Office 365 (and how to avoid them)

Let's keep in mind this is usually a problem for conference rooms.  People are double-booked all the time and it's expected.

Lots of technical info there, but as with anything in calendaring you need to also put it into a social context.

The only ways to prevent double-bookings entirely in advance and at meeting creation time are:

1. Disallow recurring bookings for resources
2. Set the allowable conflict rate to 0%
3. Make the resources go through a human gatekeeper

Now the social aspect of this:  Your users are probably going to balk at any of these.  And with good reason: 

1. Recurring meetings are just so darned useful. 
2. An allowable conflict rate of 0% is highly unrealistic
3. Having someone in charge of each resource defeats the purpose of calendaring

This is also a big issue because there is no easy mechanism for individuals to scan ahead and see if there is a possible conflict on the horizon with their meetings.  One of my daughters actually has this problem with a recurring meeting at her organization.

This is what makes double-booking a thorny problem. 

Our solution based on what we've seen is to create a PowerShell cmdlet that searches for up-coming resource conflicts and informs users or alternately takes action.

It's configurable and customize-able for a variety of situations.  Since it's a cmdlet it seems to be making more headway with on-prem Exchange sites, but it there's demand for something entirely cloud-based we're happy to discuss the issue.

October 2022: We just updated our cmdlet for Modern Authentication.