Sunday, October 23, 2016
Microsoft Exchange Free/Busy
Good read: The Hybrid Mesh: why free/busy is broken and what you can do about it.
If you have any external free/busy relationships configured things can get complicated in Exchange. In truth outside of Exchange they can get almost impossible (props to Zimbra for its efforts on Exchange free/busy integration).
The short answer is that it gets really complicated (basic reason: in email systems where calendaring is an after-thought, free/busy is an after thought to the after thought).
Follow the instructions therein to have any hope of making it work,