Orphaned Public Folder mailboxes on Exchange 2016

Hi ullerdk,

to remove orphaned Public Folder mailboxes in Exchange 2016, you can use the following steps:

1. Identify the orphaned Public Folder mailboxes. You can do this by running the following PowerShell cmdlet:

Get-MailboxStatistics -Database <DatabaseName> | where {$_.DisplayName -like "Mailbox*"} | FT DisplayName,MailboxType,MailboxGuid,OwnerADGuid,Database,DisconnectDate,DisconnectReason,ItemCount,TotalItemSize,Identity,NeedtoMove,IsMoveDestinati
on,IsAbandonedMoveDestination,IsDatabaseCopyActive

This cmdlet will return a list of all mailboxes in the specified database, including their name, type, GUID, owner AD GUID, database, disconnect date, disconnect reason, item count, total item size, identity, need to move, is move destination, is abandoned move destination, and is database copy active.

Identify the mailboxes that have a MailboxType of PublicFolderSecondary and a DisconnectDate that is empty or equal to the current date. These are the orphaned Public Folder mailboxes.

1. Remove the orphaned Public Folder mailboxes. You can do this by running the following PowerShell cmdlet for each orphaned mailbox:

Remove-Mailbox -Identity <MailboxIdentity> -Force

The -Force parameter is required because the orphaned mailboxes are not in a valid state.

1. Verify that the orphaned Public Folder mailboxes have been removed. You can do this by running the following PowerShell cmdlet:

Get-Mailbox -Database <DatabaseName> | where {$_.DisplayName -like "Mailbox*"}

This cmdlet will return a list of all mailboxes in the specified database. If the orphaned mailboxes have been removed, they will not be included in the list.

Note: If you are unable to remove an orphaned Public Folder mailbox using the Remove-Mailbox cmdlet, you can try removing it using the Exchange Management Shell. To do this, open the Exchange Management Shell and navigate to the mailbox that you want to remove. Then, run the following command:

Remove-Mailbox -Identity <MailboxIdentity> -Force

If you are still unable to remove the orphaned Public Folder mailbox, you can contact Microsoft support for assistance.

You can find this link useful as a reference:
Remove orphaned Public Folder mailboxes: https://learn.microsoft.com/en-us/exchange/troubleshoot/public-folders/public-folder-migration-errors