Outlook Delegated Calendar : Limited to 12 months

I came across a quite peculiar problem today where someone was unable to go back in someone’s calendar if the appointment span more than 12 months ago, so obviously off the blog-o-sphere I go......

📆 Calendar : Only  going back 12 months?

They could go back 11 months but when they approach the 12th month, the calendar magically turned to being empty, I originally wondered if messages had been archived from the calendar, but that is unlike the calendar. Usually the appointment are there until they deleted and we don’t have an archive in policy set up to enforce 12 months.

💵 Caching Policy's in Outlook?

Customer was using Outlook so I immediately thought about removing the tick from the box in the account settings labeled as “Download shared folders” - This can sometimes help because if you have a caching limit of three months, this will remove that restriction and download more messages, but the key here is messages this does not seem to apply to calendars.

Once this box is unticked, you need to restart Outlook however, this made absolutely no difference.

Archiving Policy - that’s not set?

The calendar of the individual that didn’t go back more than 12 months was freely accessible by other delegates of that calendar just not a couple of people, so this was not a problem with the calendar or archiving of events within the calendar.

New functionality, limiting tick boxes 

I did remember about a magical little tick box in Outlook that is labeled as “Turn on shared calendar components” - you can see this option clearly outline below…. where you need to open Account Settings then:

1. Click on your mailbox
   
2. Click More Settings
3. Click Advanced
4. Untick "Turn on Share Calendar Components"
   

This is shown below in images:

Once you want, take that box and click apply, you will get a notification that you need to get in need to restart Outlook.

Disable new functionality, Restore Legacy requirements!

Once this box was removed, the calendar magically went well beyond 12 months of history, So it would appear when you took my box you’re only able to access the last 12 months of appointments and all the other ones become hidden.

The "cause" of the issue

If you do a little bit more research, you will at some point, across this article about those calendar improvements:

Shared Calendar Improvements' to help with syncing/searching issues in the legacy MAPI Shared Calendars, and realized that the new 'Shared Calendar Improvements (REST)' option allows delegates to see all future appointments, but limits them to only be able to see or search 12 months of history

Powershell : Fix without "turning it off"

If you wish to fix this with Powershell and leave this option enabled, as I am sure some people will require the "new" features but want to go back in time like over 12 months.

If you need to fix this with Powershell then first you need to run this command:

Get-MailboxFolderPermission -Identity lee@croucher.cloud:\Calendar | fl

This will return something like this, here you need to ensure that the user has delegate permission to the Calendar, this is in bold below, and here we can see "Chief Bear" is a "Delegate"

Identity               : Lee:\Calendar
FolderName             : Calendar
User                   : Chief Bear
AccessRights           : {Editor}
SharingPermissionFlags : Delegate, CanViewPrivateItems
IsValid                : True
ObjectState            : New

Then we need to find the FolderID for the delegated mailbox with this command, remember here you have to use the delegated mailbox not the owner:

Get-MailboxFolderStatistics -Identity chief.bear@croucher.cloud -FolderScope Calendar | Format-List Name,FolderId

This will return a list of delegated calendars for that user, so for the chief.bear calendar you are looking for the entry that specifies "Lee" as below:

Name     : Lee
FolderId : LgAAAAAFEEkJufoCQ4UUkg58OUVdAQAqoO+3FhofSafKU0nA8ZDpAAPqAMyuAAAC

This FolderID will then drive the next step and command, now we need this command, but remember to get the flow the correct way around and then notice the "date" which will be in MM/DD/YYYY format as we are all American.

Set-MailboxCalendarFolder -Identity <delegate_email>:<sharedcalendar-folderid> -SharedCalendarSyncStartDate (Get-Date "4/22/2018 12:00 AM").ToUniversalTime()

That means if we take the example from above the the syntax for that example will be as follows to synchronise back to the 22nd April 2018 from today:

Set-MailboxCalendarFolder -Identity chief.bear@croucher.cloud:LgAAAAAFEEkJufoCQ4UUkg58OUVdAQAqoO+3FhofSafKU0nA8ZDpAAPqAMyuAAAC -SharedCalendarSyncStartDate (Get-Date "4/22/2018 12:00 AM").ToUniversalTime()

This will tell Exchange to synchronise the calendar and it may take some time to get all the data from "previous years" back into the Calendar view - this will also depend on bandwidth and other factors beyond your control.