Users can see only basic free/busy mailbox information in a remote forest in Microsoft 365
Article
Applies to:
Exchange Online
Original KB number: 3079932
Symptoms
In Microsoft 365, a user can see only basic free/busy time information about a mailbox in a remote forest by using Scheduling Assistant.
Cause
The default permissions on the Calendar folder in Microsoft Outlook determine the level of free/busy information that's displayed to users in a remote forest by using Scheduling Assistant. Users who are granted additional free/busy and folder permissions do not see any detailed information in Scheduling Assistant.
These are the Free/Busy permissions:
Free/Busy time
Free/Busy time, subject, location (Limited Details)
Resolution
A user may have additional permissions to a calendar folder. For example, a user may have editor, reviewer, or contributor permissions. However, this behavior doesn't change the free/busy information that's shared in Scheduling Assistant in Outlook across forests.
Note
An organization relationship is necessary to share free/busy information in an on-premises environment in a hybrid scenario. Please see the "More Information" section.
For example, if the default permissions are set to Free/Busy time, all users in the remote forest see only the free/busy time:
The cross-forest user cannot open the calendar directly and cannot view details based on their individually granted permissions. However, they can do these things by adding another folder in Outlook. To do this, a user selects File > Open > Other User's Folder. If the cross-forest user is granted reviewer or other permissions, the user can see details about the items in the calendar.
Note
Granting the Free/Busy time, subject, location (Limited Details) permission is insufficient in a hybrid environment. The user has to be granted at least Reviewer permission to view calendar item details.
The user may see the subjects of the meetings from the calendar:
The user can also open and change calendar items:
Note
Folder-level permissions are transferred when a mailbox is migrated to the cloud. Or, the permissions can be added if the object that represents the other user is mail-enabled and can be monitored by an access control list (that is, if the value of the msExchRecipientDisplayType attribute is set to -1073741818).
More information
The administrator controls the level of the free/busy data to be shared by using the settings on the organization relationship. The user controls the level of free/busy data to share with other users by using the default permissions on the user's calendar folder.
For administrators
For free/busy information to be shared between an on-premises environment and the cloud (hybrid), an organization relationship must be created. The properties that control the free/busy data shared across the forest are as follows:
FreeBusyAccessEnabled
FreeBusyAccessLevel
FreeBusyAccessScope
The free/busy access level can be set to three values that correspond to the levels available to users in Outlook:
None
AvailabilityOnly (Free/Busy time)
LimitedDetails (Free/Busy time, subject, location)
Sharing policies will function similarly for remote organizations. For more information, see New-SharingPolicy.
For users
The user controls how much free/busy information is displayed to users in a remote forest by using the Permissions tab in Calendar Properties in Outlook.
Scheduling Assistant displays the free/busy details that are configured by using the default permissions:
Microsoft Graph provides access to data stored across Microsoft 365 services. In this module, you'll learn how to access Microsoft 365 data to show a user's default calendar in a JavaScript application by using Microsoft Graph APIs and SDKs. To make sure that the web app only shows what's immediately relevant to the user, you'll access and display occurrences and instances of events for a given period.