How to Add a Company Holiday Calendar to All Users' Outlook Calendars in Microsoft 365 Tenant

Question

What is the process to automate add a Company Holiday calendar to all users' Outlook calendars within a Microsoft 365 tenant? The organization is cloud-native and utilizes Intune for management.

Answer 1

The easy way would be to send a event for the selected timeframe to all users within the company, perhaps leveraging a dynamic group or similar. You can even leverage the "direct to calendar" functionality to make sure users do not have to accept the invite: https://learn.microsoft.com/en-us/exchange/security-and-compliance/mail-flow-rules/use-rules-to-add-meetings

If you want more control or to create the event directly in user's calendar, you can use an EWS- or Graph API based solution. Here's an example: https://github.com/David-Barrett-MS/PowerShell-EWS-Scripts/blob/master/Legacy/Import-CalendarCSV.ps1