We've made major updates to the way Outlook for Windows connects to and updates shared calendars. These improvements are available for Outlook 365 customers to preview with the latest Monthly Enterprise Channel or Current Channel update, and Semi-Annual Enterprise Channel update starting with version 2008.
This article provides details about how to turn on and turn off these shared calendar improvements in Outlook for Windows.
For technical details about what's changing with calendar sharing in Exchange Online or other Outlook applications, see Calendar Sharing in Microsoft 365.
Turn on shared calendar updates
We have introduced a new option in the Exchange Account Settings dialog: Turn on shared calendar improvements (preview).
Note: This option will only be available to people using Exchange Online. There are no changes to shared calendars when one person's calendar is hosted in Exchange on-premises..
In Outlook, select File >Account Settings >Account Settings. You will see a list of your email accounts.
Select the Microsoft Exchange account that you use to manage someone else's calendar and choose Change....
Choose More Settings, followed by the Advanced tab.
Select the checkbox next to: Turn on shared calendar improvements (preview).
After restarting Outlook, your updated shared calendars will be annotated with "(preview)" when viewing your Calendars. This lets you know everything was set up correctly and that these shared calendars are using the new improvements.
Opting into this preview experience does not impact your experience with your own calendars and you can go back at any time.
Not seeing (preview) for one of your shared calendars?
The shared calendar improvements are only available for calendars shared between people using Exchange Online. If the person who has shared their calendar with you is using an Exchange on-premises mailbox, that specific shared calendar will not be eligible for these improvements.
If the shared calendar is hosted in Exchange Online, and the calendar owner has specifically granted you permissions to their calendar, please close and reopen the shared calendar to upgrade.
Navigate to the Calendar module and find the shared calendar you want to upgrade.
Right-click on the shared calendar and select Delete Calendar.
From the ribbon: Choose Add > From Address Book.
Find the name of the person who has shared their calendar with you and click Calendar.
Click OK to close the dialog.
After a few minutes, the shared calendar will reappear in your Calendar list and should now have the (preview) annotation.
Turn off shared calendar updates
If you tried the shared calendar improvements, but they didn't work for you, please let us know through Outlook in-app support.
To turn off the shared calendar improvements, follow the same instructions as above, and unselect the checkbox next to: Turn on shared calendar improvements (preview).
Using Group Policy
In addition to the new option, IT admins can use Group Policy to configure how Outlook connects to shared calendars.
We have introduced a new Group Policy setting: REST updates for calendars. This setting is already available in the Group Policy Administrative Template files (ADMX/ADML).
When this new policy is enabled:
The Turn on shared calendar improvements (preview) checkbox is enabled for all users. The UI checkbox is checked and disabled, so end users cannot turn off the preview.
When this new policy is disabled:
The Turn on shared calendar improvements (preview) checkbox is disabled for all users. The UI checkbox is unchecked and disabled, so end users cannot turn on the preview.