I recently had a user complain that he was not able to share his calendar information with his boss in Outlook. Upon checking I noticed that the affected user’s mailbox is hosted on Exchange Server 2013 and the boss’s mailbox is hosted on Office 365 cloud. Our environment is in an Exchange Hybrid scenario with Office 365. The user was able to share just the availability information but whenever he selected limited details or full calendar details the sharing failed.
The error the user had received when selecting Limited details or Full details was as shown below:
I had already confirmed that free/busy is working cross premises as expected. When researching on this issue I came across this Microsoft article that suggested to select the recipient through Global Address List. However, this did not help me. Then finally I noticed another article here that suggested to check the Sharing Policy assigned on the user mailbox.
I ran the below command and identified that the user is assigned to the Default Sharing Policy.
Get-Mailbox user | fl *sharing*
At this point I navigated to the Exchange 2013 Admin Center -> Organization Configuration. The Default Sharing Policy was found in the Individual Sharing section.
I then edited the Default Sharing Policy configuration and noticed that only free/busy information is allowed to be shared with all domains. This was the reason why the user was able to share Availability information only with his boss and not limited/full calendar details.
Inorder to fix this issue and if your organization permits, you can either edit the Sharing with all domains sharing rule and select the appropriate permission level under Share your calendar folder and save the settings as shown below:
or
you can create a new sharing policy for the specific domain (in this case your Hybrid/Split domain) and select “All calendar appointment information, including time, subject, location and title”. This is the preferred option.
Save the settings. This should fix the sharing issue.
Anish Sam Johnes 