Works on Outlook on the Web and Outlook Application
Open Outlook.
Enter Calendar mode.
On the Home tab click Add Calendar/Open Calendar and select from Directory/Address Book...
Outlook on the Web
Outlook Application
4. Browse for names or type them in the Search box.
5. Double click the name required and click OK.
6. The calendar has been added under the Shared Calendars heading.
Please note that sharing calendars externally is disabled. The reason is that there are calendar invites that include attached documents. These documents may include sensitive information or can introduce viruses. Other organizations with exchange can see our free/busy. We are unable to adjust this policy for individual users.