Exchange Online shared calendars on mobile devices

Iron Contributor

Earlier this week we had a few users start to notice other users' meetings showing up on their calendars on the native iOS calendar app and the Outlook for iOS app.  I experienced the issue as well.  When I opened the Outlook app I could see 3 of my colleagues events on my calendar that I was not part of.  I had recently looked at those calendars via Outlook on my PC.  Today I noticed that someone else had posted about the issue on Twitter.  The calendars are easy to remove and I am only aware of 1 instance where the calendars returned on the mobile device.  Does anyone have any details about a change that Microsoft would be rolling out that would have caused this?  Anyone else experience the issue?

24 Replies
Thanks, Mike. That's a good summary of the changes.

Arnold, does that make sense now? Also, would you mind direct messaging me your support case number? Pointing to this thread shouldn't be the resolution, and I want to be sure all agents understand this scenario. Thanks!

Yes, thank you @Mike Tilson and Julia. It does clear a few things up. The only thing is how to remove the calendars from the Native IOS calendar app? We do not see a way of doing this besides removing it from outlook or owa and then letting it propagate. Sure the case is 117112717223740. Thankfully it has now been escalated to another engineer and hopefully we can get this answer in a more formal format so that we can dispense to management.

To remove from the native iOS calendar app do the following:


  • Open the calendar app
  • Select Calendars at the bottom
  • Select the circled i beside the calendar you want to remove
  • Select delete calendar




following above instructions to remove the calendar from iOS calendar app did not work for us - with iOS 11 the delete option does not show up. However, one would be able to deselect the calendar for visually showing up in the native calendar app. Be aware that due to some iOS bug users with an Apple Watch seem to get still reminders for meetings set up in the calendars that they chose to not show in the calendar app (that is, getting reminders on the Watch, as well as new calendar invites on both Watch and iPhone).


The only practical way to remove another persons calendar from your mobile (if synchronized via Exchange ActiveSync) in our case was to let users log in to OWA, then have them remove the additional calender from the OWA calendar view. This would not remove the calendar from Outlook clients on PC or Mac, but remove it from OWA and ActiveSync devices. Just deselecting the "Show calendar" option in native iOS calendar app was not the way to go for us due to the iOS bug.


It would be great if these side effects could be mentioned in the calendar access invitation emails that get sent from O365 (like, "if you click on the button to accept the access invitation be informed that this will add the persons calendar on your mobile phone") or just name the button "add calendar to all my devices". 


Issues around this behavior were difficult to analyze due to the fact that only peoples calendars were affected that recently had been granted access to, or changed access rights, as well as mostly manager calendars being affected. People and our service desk would typically have checked the access rights on the shared calendar itself instead of the reporting users calendar list in OWA (in our organization, most people would not even know about OWA). Hey Microsoft, there's room for improvement here.

We seem  to have run into this and wondering if there is a powershell Cmd to remove it from OWA? @Thomas Mendorf