Copilot for Microsoft 365 Tech Accelerator
Feb 28 2024 07:00 AM - Feb 29 2024 10:30 AM (PST)
Microsoft Tech Community

Shared calendars now sync to mobile phones


We are rolling out a feature update that enables shared calendars to sync to mobile phones. This update will make it possible to sync all your Office365 shared calendars to your mobile phone for any permission level (view, edit, or delegate permissions). In addition, you can now share a calendar or accept shared calendar invitations from Outlook on iOS and Android.


Existing shared calendars will not be upgraded as part of this change, and they will continue to sync only to Outlook on the web, Windows, and Mac. Only shared calendars that are accepted after these changes are released will sync to mobile phones.


The shared calendar will only sync to mobile phones if:

  • The calendar is shared between users who are both hosted in Exchange Online
  • The calendar is accepted from a sharing invitation using Outlook on the web, iOS, or Android


We'll be gradually rolling this update starting on 9/18 and rollout will be completed by 9/22.


You can find more details about shared calendar improvements at the article located here.

117 Replies
Does this cover Shared Mailboxes as well? Total game changer on the mobile side.
This sound great! Was their meant to be a link to an article? Thanks

I was doing some testing this morning.  I couldn't find out how to make it work with a calendar from a "Shared Mailbox".  I didn't see how in OWA or Outlook iOS to send an invite to another user. That was part of the stipulation of how it works - you need to send a sharing invite using a mobile app or OWA and the person needs to accept the invite in OWA or an Outlook mobile app.


I did however get it to work with a calendar that I created under my own 365 account. That calendar showed up under my account settings in Outlook iOS then I invited a co-worker.  Then he accepted the invite via Outlook iOS.  He could then see my shared calendar in his Outlook iOS app, native iOS calendar (!!) and Outlook PC calendar.


If someone can confirm that this SHOULD work with a "Shared Mailbox" calendar and provide some instructions on how to do that, what would be awesome!




Hi Andrew, John, & Jason,


Thanks for your feedback! To answer the questions:


Support article link:

Good catch on that link. Sorry about that -- it's been updated to point to this support article.


Shared mailboxes

  • Yes, it works for shared mailboxes as well.
  • You can share the calendar from any Outlook application, as long as you send a sharing invitation so that the recipient can accept from Outlook on the web, iOS, or Android. This applies to user, resource, and shared mailboxes.
  • From Outlook on the web: Login to your own mailbox first, and then click your picture in the top right to view Account options. There will be an option to "Open another mailbox". Enter the shared mailbox name to login to the shared mailbox via OWA. After you're logged into the shared mailbox, you can navigate to the Calendar module & share the calendar to yourself or to other users. Then you (or the other users) just need to accept the invitation from Outlook on the web, iOS, or Android.
  • From Outlook on Windows and Mac: These clients only offer an option to send a sharing invitation for read-only permissions. Accepting invitation sent from Windows/Mac will work, but people have asked how to grant edit permissions for a shared mailbox calendar (since it doesn't currently send an invitation)? A workaround would be to (1) send a sharing invitation from Outlook on Windows/Mac for read-only permissions, (2) update the calendar permissions in the Folder Permissions dialog (that doesn't send an email) to Editor, (3) have the recipient accept the calendar from the original sharing invitation. Even though the original invitation was for read-only permissions, the calendar will be added as editable because that is the effective permissions.
Will this be available for a hybrid Exchange environment?

So this is a great update and long over due, however I can not help but feel that this feels clunky. The fact that you can not use previously shared calendars and you have to accept it from the web or iOS is odd.  


Is this some sort of desktop issue this will be fixed at some point with Windows and Mac?

Hi Will,


I agree that the story should be simple: share & accept from any client, and have the awesome new experience everywhere. That is certainly the plan, and where we want to be, but it's a journey to get there. Today's release is just step #1 :-).


Some more details:

  • Windows & Mac: The web, iOS & Android clients were able to finish their changes sooner so that's why it's currently accept from one of those three. We're working on a way to detect accepts from Windows clients without any client changes (including legacy clients like Outlook 2013) and plan to release those changes in Q4, which would change the statement to "Accept from any Outlook client but Mac". The Mac client has always stored the list of shared calendars in a local list on the computer, so there's no magic we can do in the service to detect those accepts. To include Mac in the list of clients that you can accept from, changes are being made in the Mac client. Updating shared calendars support (for sharing, accepting, & syncing) is a top priority for Windows & Mac, and you can expect more updates about those clients as timelines become clearer.
  • Existing shared calendars: We wanted to have an "opt-in" model for a few months before we started upgrading existing calendars. There are hundreds of millions of shared calendars in the system, so it will take a while for us to upgrade them all. Having an early, opt-in release allows us to get feedback before we start automatically upgrading all shared calendars. But existing shared calendars will be automatically upgraded in the future (no timeline yet though).

Hi Kenn,


The improvements are only for calendars shared between Exchange Online users. If you have a hybrid setup, but both users are hosted in Office365, they would have the improvements. But there is no change to experience if one (or both) of the users are hosted on-prem.


It won't be coming to future on-prem releases because we are unable to support these improvements when on-prem is involved -- many of the improvement rely on functionality that is only possible when both mailboxes are in the service, such as instant syncing.

Great to see this functionality on the way!


How can I send a sharing invite from a shared calendar that doesn't have an attached shared mailbox?

Hi Julia,

Thanks so much for the additional information.  We've been looking forward to this feature for a long time.


I'm currently testing with a "Shared Mailbox" calendar.  I followed your steps for sharing it via "Outlook on the Web (OWA)" and that worked just fine. 1) Login to my OWA, 2) 'Open other user mailbox' and get into the shared mailbox 3) go to the calendar and hit the Share button.  I can even select edit permissions and they worked great.  The person that accepted the invite in Outlook for iOS was able to see the calendar in Outlook for iOS, Outlook for PC and even iOS native calendar app.  They made some changes and it successfully synced back.


However I'm still not having any luck trying to send a sharing invite from Outlook on the PC. I'm on the latest Outlook 2016 click-to-run edition so I should have all of the latest features.  Through the Office 365 admin portal Shared Mailbox interface, i've given myself full permission to the mailbox and I can see the calendar in Outlook for PC. But when I right-click on the calendar and hit Share, my only option is to "Email Calendar" which I believe just sends a static copy of my calendar via an ICS attachment. The "Share Calendar" option is greyed out.  


If someone has had luck sending a sharing invite for a "Shared Mailbox" calendar via Outlook for PC, please let me know how you did it. 


Thanks again!



Exact same problem, admin user couldn't do it either.

I started seeing this on September 6 after one of my end users brought this to my attention. After finding zero info on this I figured this was a new feature but my question is always this.


Could these posts come out earlier next time?

Does this include the ability to open a colleague's calendar? This has been a huge gap in the apps for years - really hope it can be added for Outlook for iOS/Android: go to settings, open shared calendar, type in the name of the individuals name and if you have permissions, it opens - just like on Outlook. My users have been asking for this for a long time.
To echo comments below -shouldn't have to be reliant on this invitation exclusively as a result of this new update, but based on the existing permissions that have (in some cases) been in place for years, just relegated to desktop versions of Office (or a web browser).


So we just tested this today and the shared calendar did show up in the Outlook iOS app.


However we discovered a possible BIG bug.  The shared calendar also shows up and is viewable in the default iOS Calendar app, and while that is ok, I was able to delete and add items from the shared calendar even though I did NOT have any permission but reviewer.  We confirmed the settings by checking the properties, then permissions of the calendar and the delete option was set to NONE and I was labled as reviewer.  We confirmed the default and annonomous settings were set to none as well.


On the iOS app I could not delete or add anything.


We tested this on a iphone runing iOS 11

[Apologies for the lengthy reply but trying to address all the above questions]


Sending invitation for a shared mailbox calendar from Outlook on Windows:

Cc: Jason, Hamish

Let me follow up on this, and get back to you. We are working on updating the sharing experience in Outlook on Windows, so I might have been testing it out with early bits. In the meantime, sharing from OWA will always work.


Earlier notification of changes

Cc: Greg

What I think some of your users were seeing was that opening another person's calendar synced it to mobile. Since early 2017, accepting a shared calendar with view or edit permissions synced it to mobile, and we made what we thought was a bug-level fix to align the two "add calendar" actions (accept & open) to have the same behavior (sync to mobile). We immediately heard from admins that we should have notified them of this, and many users said that they didn't want these opened calendars to sync to mobile. You're absolutely right that I failed to give enough advance notice of that change, and I promise I'll do better next time. Based on the feedback from admins & users, we have disabled the functionality that enabled "open calendar" to also sync the calendar to mobile. Right now, only explicitly accepted calendars will sync to mobile. We do plan to re-enable the "open calendar" functionality in the future, but we need to talk to more users about expectations here. As you can see from Chris' comment, some users expect "open calendar" to also sync to mobile :-). In this TechCommunity post, I share more details about the changes that we enabled & then disabled. Would mind DM'ing me and sharing what your thoughts are on how we should handle "open calendar"?


You might be thinking, "so if calendars have been syncing to mobile since early 2017, what is this announcement about?". The major changes that came out this week was that delegated calendars would also sync to mobile (previously only view/edit was supported), and the Outlook on iOS or Android apps were updated to allow users to accept sharing invitations & also show an indication to delegates who a meeting invitation was received for.


Opening another user's calendar

Cc: Chris

We had also thought that "open calendar" and "accept" should both result in syncing from mobile. We made a change a few weeks ago that enabled that functionality. However, it sounds like there's a split among users & admins about whether or not "open calendar" should also sync to mobile (even on this thread there's differing views!). So we disabled the update for "open calendars", and right now, only calendars that are explicitly accepted from a sharing invitation will sync to mobile. There's more details in this TechCommunity post. Would mind DM'ng me and sharing what your thoughts are on how we should handle "open calendar"?



Seeing option to "edit" a read-only calendar in native iOS app

Cc: Will

This is mentioned in the support article (in the section titled "Third-party clients"). Unfortunately the native calendar apps that sync via EAS do not differentiate between read-only or read-write calendars and treat all as read-write. Users will see the option to edit a read-only calendar, or event to RSVP to a meeting invite. However, the server rejects these because the user does not have edit permissions, and nothing is actually written to the service. The "edits" are local only in that app. If the calendar recipient goes to view the calendar in an Outlook app, they won't see the edits. This is a reason that we recommend all shared calendar users to use the Outlook mobile apps because they do differentiate between the different permission levels, and read-only users won't be offered any edit options in the Outlook on iOS and Android apps.


With reguard to the native iOS calendar app deleting/adding items and the server rejecting the request based on my permission that is not the case per our testing.  


I do not have permission to add or delete anything, just view.  However when using the native iOS calendar app I was able to delete items i did not create and add new items to the calendar.  Both of these changes synced to the server calendar and the users could see the changes in Outlook 2016 for Windows.

Hi Will, are you sure that you don't have edit permissions via Full Access or via a security group somehow? Would you please DM me the email addresses of the calendar owner & the calendar recipient?

Sent you a PM and yes I show as "Reviewer" for this calendar shared to me from Outlook 2016 for Windows.

Follow-up for everyone, it appears the account did have full permission even though it was not showing it in the calendar.  After more testing the permissions are working correctly and only giving us view access as needed   :)