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.

114 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   :)



We are loving the new shared calendar features, as we've discussed the past week.


Do you know if there are plans for similar functionality around using the mailbox portion of a "Shared Mailbox"?   We were so exicted to see that the calendar part worked but then we noticed that we can't see anything email related in the mobile apps.   And i didn't see any way to send a sharing invite from my mailbox view.


We still need a solution to be able to see a shared email account like sales@company.com on a mobile device.





How about shared contacts, will this apply to them as well? If so is them method to add them the same as the calendars?


Apologies for delay in responding! Have been busy at Microsoft Ignite conference this week.


@Jason Hartman
Yes -- this update works for calendars from user mailboxes, resource mailboxes, or shared mailboxes. You just need to send a sharing invitation from the shared mailbox so that the user can accept on web, iOS, or Android. The easiest way to send an invitation from a shared mailbox is to use Outlook on the web to open it. A little earlier in the thread I gave instructions on how to do that, and realized it's not possible (yet) from the Windows client, so you will need to share from the web.


Part of the thinking behind syncing "opened calendars" (not just "accepted calendars") to mobile phones was to make it easier for this to work for resource & shared mailboxes, so that you didn't have to login & send the sharing invitation. As you know, we disabled the "opened calendars" part due to feedback, and will re-enable it when we only sync calendars that you have explicit permissions to (rather than permissions via the default user).


@Becky Martin
There are no plans to support this for shared mail folders or shared contact folders. The best way to give feedback on those plans is to upvote the feature on outlook.uservoice.com in the iOS & Android forums.




is there some possibility to turn off this feature? We have got problem in our company with Android users - they have synced everything in one calendar, so they can't turn off shared mailbox in their smartphones, because it is part of one calendar. So they have "spamed" calendar on Android with foreign events.

Thank you very much for informations,

Jakub Krňák


Hi Jakub,


It won't be possible to disable this at the tenant level. We hope that the native calendar apps start showing the different calendars, but an alternative would be for your users to use the Outlook for Android application which does differentiate between calendars.




Thank you very much for your reply Julia, I will informate my coleagues.

There is problem only on Android, iOS is OK :)


Have a nice day,


Same here. Users get confused that calendar events which they do not planned are in their calendar also with reminders for some of our users. Also getting just open calendar on Outlook and after that it get synced is odd for some.


Yes Petr, exactly same here. And you know, when I say them "just install Outlook app, I use it too, it's better" ... they say "I like this native app" or "I am accustomed to this app" :D

So I hope for solution in next Android update.

@julia Is it possible to mute notifications from the other calendars. I have a person who is getting meeting reminders on their mobile from these other sync'd calendars. How do we stop that?

@Greg Tiber - That should not be happening because on the sharee copy of the calendar, we set the popup reminder value to "None" for all events. Can you send me a private message with a screenshot of what the event looks like in Outlook on the web?


Hi Julia, some of our customer experience the same on Windows Mobile with Outlook. They receiving notifications about events from shared calendars. I will try to catch the details with customers and send you these.




Thanks for the heads up on the article re: new features.


I was particularly interested in the "instant sync" feature.  I have been working on a project (for a couple of years) that really needs this capability.  Briefly it involves an application that publishes highly changeable schedules to a calendar and then shares these calendars with selected individuals through their own accounts.  As long as the calendars are in the same tenant this works fine on O365 and updates almost istantaneous.  When the calendars exist in different tenants the result (as you know) is that the calendars take 4+ hours to sync.


When I read the referenced article, I noted that although "instant sync" wasn't available between two O365 accounts (yet?), however it was available between Oulook.com and O365.  Unfortunately I missed the part of the article that said that "instant sync" was not compatiple with EWS. 


NOTE: Exchange Web Services (EWS) API will not support instant syncing.


We are using EWS to push this data to the first calendar so that it can be shared to others.  

 We did observe a bunch of anomolies when we tried this between an Outlook.com account and a O365 account. 


With that not working, we  decided to try the MS Graph api, however, I thought I would check to see if the would have the same issues as EWS had with "instant sync".


Any other suggestions would also be appreciated.


Thanks for taking all the customer feedback to advance the O365 platform.






Hi Bill,


  • We do plan to support instant sync'ing across tenants in the future. Today, instant syncing is supported only when sharing within an Office365 tenant, or sharing from an Outlook.com account to another Outlook.com user or an Office365 user.
  • Clients also need to make updates to take advantage of instant syncing. So even if two users are in the same tenant, they won't (yet) see updates instantly in Outlook on Windows or Mac.
  • If you're using EWS, you can edit the owner's calendar & it will instantly sync to other sharees (assuming the above two bullets are taken into account). However, if a recipient has edit access to the calendar, you cannot use EWS when the recipient is editing the calendars.
  • I'm not sure when you tested, but we just recently enabled instant syncing for sharing from Outlook.com to an Office365 user, so that might have been the issue.
Julia: I tried to send you a private message on this forum, but it does not allow me to do it. Can I contact you on LinkedIn or etc?
Sure thing!

I first encountered the same problem with the calendar events of other persons in my own calendar using Samsung Calendar in my old Samsung S4 with Android 6.x. One week ago I started to use a Samsung S8 with Android 7.x and I installed Outlook on it. After using it for one week I suddenly had a mix of one other person's events (a shared calendar in my own organization that I had opened once and closed) and my own events. It seems like the last calendar of the other person I have opened with my Outlook on Windows 10 always get synchronized with my mobile Outlook on Android. I have found no way to stop this from happening. My mobile Outlook has become a mess, although my Outlook on Windows 10 is as tidy as before.

In the new Android version I found that I can tick off the other Calendar that has come up after opening it in Outlook for Windows. So, the problem how to get it off is solved.

Hi Julia

I have a problem. I used outlook.com for a longer time and it was just fine. But after the big update of outlook.com, the ability to choose my own e-mail (like stefan.k....@synor.ch) as sender was lost. In outlook.com online it works, but if you use Outlook Desktop, it won't work anymore (before I did work!).

As second I shared my calendar with my girlfriends outlook.com account (she uses the iPhone calendar) and it worked pretty well. This did work before the change of outlook.com and after the change it worked also well.

But because I'm self-employed, I want to use my own e-mail with my own domain (like I said: stefan.k....@synor.ch instead of stefan.k....@outlook.com).

That was the reason that I changed to the paid Exchange Online Version.

I thought that with the paid version, all would be possible - but sadly it isn't!


Now I'm able to have my own sender e-mail with own domain, that works.

But this does not work with the calendar share to an external outlook.com address!

That means it only works if I pay for another Exchange Online user for my girlfriend!


But I found this totally annoying!

If the new outlook.com is based on the technology of Exchange, it would be easy to offer this sharing function also for Exchange Online !?


Could you add this please?

Because I pay now, but I haven't the full functionality.

Except you say that they will soon reintroduce the function in outlook.com, where you can define your own senders also in Outlook desktop again. Then I would switch again to this free offer.


Thanks a lot for your answer





In my profile here, there my name will be "null null". I can't change it to "Stefan Krapf". It won't be saved... :(


Hi Stefan,


I would recommend reaching out to Outlook.com Support for help with this issue, as it will require some debugging with a support agent. What you need is true support for custom domains, which is not specific to the calendar.


Also, your question is not related to the content on this post (which is about shared calendar calendars sync'ing to mobile phones). In the future, please create a new post to help keep the forum threads organized. :)




I have shared calendars showing up on the app widget that I have deleted.  I do not want to see these items but can not find a way to get rid of them.


Hi @Judson Walker Please try deleting the calendar using one of the Outlook apps. If you're still hitting an issue, then it would be good to reach out to Customer Support. This forum is not intended to be a "support/debug" channel and more of an "information/how-to" channel.


This is a good option. However it would be much more beneficial, if the appointments are differentiated by colors - one color for your personal calendar and another color for the shared calendar. Presently both are shown with the same color and the calendar seems to be in a mess, at least on the mobile view.


Hi Abhay, it sounds like you're using a 3rd party calendar app. I have heard many Android apps show all the events as if they were the same calendar, which makes all the events show in the same color. This is an issue with the app you're using, not the Office 365 implementation. If you add your account to Outlook on iOS or Android, you'll see that the calendars are separate and you can choose different colors.


If existing shared calendars will not be upgraded as part of this change, am I reading it correctly in meaning my current user's personal calendars that they have shared out in the past will not be accessible via mobile?  If that is the case is there any way to get my users personal calendar's shared out and accessible by mobile by perhaps unsharing and resharing again??  Or am I just stuck with not being able to get them on mobile?


Does this include contacts as well or only calendars?

Hi Becky, it is calendar only. We'll eventually automatically upgrade already-shared calendars but are not planning to do it anytime soon.

And yes, you can absolutely self-upgrade by re-sharing & re-accepting. At this point, you just need to accept from Outlook on the web, iOS, or Android to self-upgrade so that the shared calendar syncs to your mobile phone.

That's a great feature - but only if you want it.


How do you turn it off? I don't want ALL the shared calendars showing on my mobile calendar. The only option is to turn off the "calendar" which incorporates my personal calendar and all shared. This is rather annoying, so hopefully there is a way to do this without actually deleting the shared calendars from within my O365 account.



Hi Allan, there is no way to disable this. We have to promise users that they will have the same calendars sync to all of your devices (just like they experience in every other calendar service). Feel free to private message me with more feedback about your use cases for not wanting all calendars to sync to all devices.

Hi Julia


Thanks for the reply. But as you know in Office365 OWA and Outlook you can turn these calendars on and off as required, as I doubt anyone wants all of their shared calendars on at the same time. Especially on a mobile device where the screen size is so much smaller I cannot see half of the entries on my calendar anymore. This really should be looked at and have a function where you can change what you are viewing.

Hi Allan, I completely agree with you. In the Outlook mobile clients on iOS & Android, you can select/unselect calendars just like you can in all the other Outlook clients. You can also select/unselect calendars in the native iOS calendar app. I'm not sure how all the native Android apps work across manufacturers, but that is just a limitation of the app you're using. I recommend using the Outlook mobile apps myself :)