Assign User calendar access viewing rights



We have a Microsoft 365 tenancy that was set up in 2019 by a third party consultancy. Originally, it included three domain names - one old name that was kept just in case anyone contacted us via it and two current domain names.

We have two Active Directory domain controllers at our office and the user account information is synchronised with the 365 tenancy.

Since that time I have used PowerShell to assign calendar sharing permissions between all staff. Our management had asked for all staff to be able to view all other staff calendars. I achieved this using the following command:

Add-MailboxFolderPermission -Identity john.smith:\calendar -user amanda.bloggs -AccessRight Reviewer

This works fine.

Last year I added a new domain name e.g. to our 365 tenancy. It has just two user accounts set up to use it: e.g. and they are able to send/receive email without problems. Today, I was asked to set up calendar sharing between these staff and the rest of the organisation.

When I issued the PowerShell command the following error was displayed:


PS C:\WINDOWS\system32> Add-MailboxFolderPermission -Identity new.user:\calendar -user amanda.bloggs -AccessRight Reviewer
The specified mailbox Identity:"new.user" doesn't exist.
+ CategoryInfo : NotSpecified: (:) [Add-MailboxFolderPermission], ManagementObjectNotFoundException
+ FullyQualifiedErrorId : [Server=CWLP123MB3284,RequestId=a35dfabe-6b62-49b0-a911-2f61bd3c7f23,TimeStamp=10/12/202
1 09:10:54] [FailureCategory=Cmdlet-ManagementObjectNotFoundException] 3959D584,Microsoft.Exchange.Management.Stor
+ PSComputerName :

To check the command was correct I substituted a new member of staff user account name that uses one of the original domain names and it worked fine:

PS C:\WINDOWS\system32> Add-MailboxFolderPermission -Identity michael.brown:\calendar -user amanda.bloggs -AccessRight Reviewer

FolderName User AccessRights SharingPermissionFlags
---------- ---- ------------ ----------------------
Calendar Amanda Bloggs {Reviewer}

PS C:\WINDOWS\system32>

The difference is that I added this fourth domain name to our tenancy (not the consultancy) so I don't know if there was a specific sharing attribute setting that I have missed that I should have configured. When I added it I used the connector available via GoDaddy to automatically set up the email. However, this had to be edited because we use Proofpoint Essentials to filter our mail so had to change mx records.

Finally, I am not well versed in Microsoft 365. I don't understand why the Powershell response states the user does not exist.

Can anyone help me to resolve this, please?

Thank you.


2 Replies
best response confirmed by PK Player (Contributor)
First, simply try using the full address of the user, as in\Calendar. The Calendar folder itself might have a different name, but that would result in a different error message.
Generally speaking, when you add a domain you need to select which services to configure it for, at that step you need to select Exchange Online. If you didn't do that, you'd be unable to use it for SMTP addresses and such though. But just in case, verify the selection under the M365 Admin Center > Settings > Domains > check the Services column on the far right.
Hello, Vasil.
Thank you for responding to my query.
I used user@domain name and it worked a treat. I checked the services status under Settings > Domains and Exchange was already checked.