Forum Discussion

Kersten_Berlin's avatar
Kersten_Berlin
Copper Contributor
Apr 30, 2024

iCalendar-Service with authorization with Exchange Online

Hallo, we have an iCalendar WebService, which we want to use in Outlook with Exchange Online. Because the data are not public, we want to restrict the access for allowed users. With basic auth (use...
exchange online
outlook
MadisonClark's avatar
MadisonClark
Iron Contributor
Apr 04, 2025

1. Confirm that the calendar is shared 
Have the user log in to Outlook Web → Calendar → Sharing → Check that external sharing is enabled 
2. Test the direct access link 
Open the correctly formatted link in your browser: 
https://outlook.office365.com/owa/calendar//calendar.ics 
opens = Permissions are correct 
Error = Administrator adjustment required 
3. Administrator quick fix 
 Allow anonymous access 
Exchange Administrator Centre → Recipients → Select user 
Calendar sharing → Set "Anonymous users can view busy information" 
4. Check organisational policies 
Make sure there is no global block on calendar sharing: 
powershell 
Get-SharingPolicy | fl * calendar* 5 Developer solutions ➔ Calendar* 5 ➔ Calendar* 5 ➔ Calendar* 5 calendar* 
5. Switch to Graph API 
Register the app with Azure AD 
Request Calendars.Read permission 
Get data using the API: 
GET https://graph.microsoft.com/v1.0/users/calendar