Fixed: Outlook Shared Calendar notifications

The Microsoft Exchange team have announced that an update to shared calendar notifications is now leaving preview and entering production. These improvements are gradually being made available for Outlook-on-the-web (a.k.a OWA), Outlook for Mac and mobile (it’s already rolled out for these two) and, finally, for Outlook on Windows.

The intention is that this is just an improvement – there should be no glaringly-obvious user-noticeable changes beyond snappier performance. There are some minor improvements, but they take the form of more intelligent handling of things like amended meetings, with fewer confusing dialogue boxes needing an answer. As an example, if you amend a long-established recurring meeting Outlook can now update it, leaving historical meetings alone, but allowing future meetings to have revised attendees/dates/times. It doesn’t break them, and most of the confusing user prompts are no longer needed.

To get an overview of what’s new Microsoft have provided this page. For a nice friendly video (which was on that page but now isn’t any more) showing how to enable it, and what’s new, there’s this link: video guide.

What’s changed?

  1. More responsive, faster updates.
    What we’ve all grown used to is shared calendars lagging behind the times – there might be changes that have happened in that calendar which haven’t yet appeared for our view of it. This leads to differing out-of-sync versions. After this change, editing a shared calendar should be as responsive as editing your own.
  2. Meeting organiser improvements.
    You can extend a recurring meeting without impacting any historical exceptions to it. If you modify the meeting’s attendee list, updates are only sent to those you’ve changed. Draft meetings will now appear in your calendar (unsent), rather than your Drafts folder. And if someone accepts a meeting but doesn’t send a response, you can still see they’ve accepted it via the ‘tracking’ tab of the meeting. One potential gotcha is that when you forward a meeting to a new attendee, existing attachments remain but you can’t add new ones. This ensures that all attendees can see all of the original attachments, with the same content.


Technical details of the changes

Attribute Old Model New Model
How a shared calendar is stored A hyperlink-like entry is placed in your mailbox. A new calendar is created within your mailbox containing a copy of the data (going back 12 months)
How a shared calendar is accessed Reads/writes the owner’s mailbox. Reads/writes local copy of the shared calendar.
How a shared calendar syncs Original mailbox is periodically polled. Changes synced instantly to your cached copy. (Push notifications used)
Apps allowing access to a shared calendar Outlook on Windows and Mac, and OWA. Outlook on Windows, Mac, iOS, Android. Also OWA, Calendar for Windows 10, and all REST/EAS apps.

Is this enabled for me yet?

Ways to check:

  1. Can you see the shared calendar on a mobile phone’s copy of Outlook?
  2. Is ‘Turn on shared calendar improvements’ ticked? (Find this in File>Account Settings> Account Settings> [your email account] >Change > More Settings > Advanced)
  3. Admins can check group policy restrictions: HKCU\Software\Policies\Microsoft\Office\16.0\Outlook\Options\Calendar
    The value ‘SharedCalendarImprovements’  controls this setting and will be set to 1 if enabled; zero if it’s disabled.
  4. Check the ‘calendar properties’ dialogue box. You will need ‘editor’ or ‘delegate’ permission to do this. If the type has changed from ‘Type: Folder containing Calendar items (MAPI)’ to ‘Type: Folder containing Calendar items (REST)’ then it is enabled.
  5. Admins can check using Powershell – use the Get-MailboxCalendarFolder  cmdlet and check the ExtendedFolderFlags lookikng for a ‘SharedIn’ value.
  6. MFCMAPI will show the shared calendar in the calendar subtree and there will be an entry in the ‘common views > associated contents’ table called ‘SharingCalendarGroupEntryAssociatedLocalFolderId’.

Can I force an update?

Requirements: the shared calendar owner is hosted in Exchange Online, and you have specifically been granted you permissions to their calendar.

The simple solution is to ask the calendar’s owner to re-share the content with you, which they can do from any Outlook application. You can accept the invitation using an updated version of Outlook to force the update to this new calendar model. To do this without the user’s intervention:

  1. Navigate to the Calendar module and find the shared calendar you want to upgrade.
  2. Right-click on the shared calendar and select Delete Calendar.
  3. Close and restart Outlook.
  4. From the Home ribbon in the Calendar module: Choose Open Calendar > Open Shared Calendar
  5. Enter the name of the person who has shared their calendar with you
  6. Click OK to close the dialog.
  7. The shared calendar will reappear in your Calendar list and should now be upgraded.

Note that there may be a short delay for the first synchronisation as the content is copied but future content changes should appear near-instantly.


Further reading: Microsoft calendar sharing

Page was amended 2nd June as Microsoft have updated the page to which I linked, and removed the video guide from their page. A new link has been added for the video.

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