EO - mailbox folder permission for Usertype unknown - how to remove ?!

Daniel Hnyk 56 Reputation points

Hello guys, i would like to get some advice, how to remove mailbox folder permission for usertype Unknown in ExchangeOnline

I am connected to exchange online via PS with prefix EO as Exchange Online, so cmdlets will start with EO, because we have hybrid environment and i need to manage both in one PS.

I have shared mailbox, where is some corrupted ACL for user group, which i want to remove.

[PS] C:\ExchangeScripts\ExchangeOnline\Resource Migration>(Get-EOMailboxFolderPermission "Mailbox") | select -ExpandProperty user

UserType RecipientPrincipal DisplayName

Default Default
Anonymous Anonymous
Unknown %GroupName%

so i am able to select this unknown UserType:
Get-EOMailboxFolderPermission -identity "Mailbox" | where {$_.user.usertype -like "unknown"}

But i cannot remove this rights, through pipeline:

Get-EOMailboxFolderPermission -identity "Mailbox" | where {$_.user.usertype -like "unknown"} | Remove-EOMailboxFolderPermission

Cannot process argument transformation on parameter 'User'. Cannot convert value "GroupName" to type "Microsoft.Exchange.Management.StoreTasks.MailboxFolderUserIdParameter". Error: "Cannot convert hashtable to an object of the following
type: Microsoft.Exchange.Management.StoreTasks.MailboxFolderUserIdParameter. Hashtable-to-Object conversion is not supported in constrained language mode, restricted language mode or a Data section."

  • CategoryInfo : InvalidData: (Microsoft.Excha...olderPermission:PSObject) [Remove-MailboxFolderPermission], ParameterBindin...mationException
  • FullyQualifiedErrorId : ParameterArgumentTransformationError,Remove-MailboxFolderPermission
  • PSComputerName : outlook.office365.com

I dunno, why it returns that error described upper....

Do you have any ideas how to deal with it?

Thanks you


Microsoft Exchange Online Management
Microsoft Exchange Online Management
Microsoft Exchange Online: A Microsoft email and calendaring hosted service.Management: The act or process of organizing, handling, directing or controlling something.
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Microsoft Exchange Hybrid Management
Microsoft Exchange: Microsoft messaging and collaboration software.Hybrid Management: Organizing, handling, directing or controlling hybrid deployments.
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Accepted answer
  1. KyleXu-MSFT 26,206 Reputation points

    @Daniel Hnyk

    Try to recover this mailbox, then check whether this "Unknown" user become visible on this permission list.

    If you cannot recover this mailbox, you can try to create a service request to Office 365 team, check whether they could delete this permission from the backend.

    If they cannot remove the permission for you, I think you may need to recreate this mailbox. In this way, all permission on this mailbox will gone. But you need to add needed permission back to this mailbox again.

    If the response is helpful, please click "Accept Answer" and upvote it.
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    1 person found this answer helpful.

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  1. Jürgen Barth 0 Reputation points

    even if the thread is old ...

    I have the same problem, did you ever solved this problem?
    I was told to reset the delegates, but this doesn´t help.