Note: This is not related to the Hybrid Exchange migration type. This deals specifically with a hybrid public folder migration, which is entirely different.
If you try to create any Public Folder mailboxes on Office 365 when hybrid mode has been set up, you will receive a 'HoldforMigration' error similar to the one pictured below. This is because the Office 365 Organization has the Public Folders configured as "Remote" so that users can access the On-Premises Public Folders. The error occurs because hybrid mode is expecting Microsoft tools to complete the migration.
In order to proceed, follow the steps below. Once these steps have been completed, hybrid mode can be re-enabled. The steps to do this are also included below.
First, take a quick look at the root Public Folder mailbox, by running from the Exchange Online PowerShell:
You will see results similar to these:
This picture shows that the root Public Folder mailbox is locked for migration. All other Public Folder mailboxes will also be unavailable.
Now look at the Organization Configuration, by running the following command from the same PowerShell:
Get-OrganizationConfig |fl *public*
You will see results similar to these:
The PublicFoldersEnabled attribute set to remote confirms that the Office 365 users are set to use the On-Premises Public Folders.
Note: Make a note of the RemotePublicFolderMailboxes value. You will need this later to allow access to the On-Premise Public Folders.
To resolve this issue, and to be able to create the Public Folders on Office 365:
- Remove all the existing Public Folder mailboxes on Office 365, by running on the Exchange Online PowerShell:
Get-Mailbox -PublicFolder |Remove-Mailbox -PublicFolder
Note: It may be necessary to run the cmdlet twice because when there is more than one Public Folder mailbox, it is not possible to delete the primary mailbox before deleting the others.
Warning: In a Hybrid scenario, where Public Folders are being used On-Premises, the Public Folder mailboxes on Office 365 should be empty and not have any relevant data. If unsure if the Public Folder mailboxes are empty, verify that they are empty before deleting them.
- Once all the Public Folder Mailboxes are deleted from Office 365, change the Organization Configuration to use Public Folders on Office 365, by running on the Exchange Online PowerShell:
Set-OrganizationConfig -PublicFoldersEnabled Local -RemotePublicFolderMailboxes $null
Warning: This will break the connectivity to the On-Premises Public Folders for all users with a mailbox on Office 365. Plan a maintenance window.
Now create the first Public Folder mailbox, and assign root permissions to this Public Folder mailbox to the admin account being used for the migration. Exact steps are provided in How do I create the Public Folder mailbox on Office 365?.
Note: Do not create any public folders in O365 manually unless migrating more then 20 GB of data. Most will then be created via mapping scripts supplied by BitTitan Support. This is covered in your migration guide.
Now revert the Organization Configuration, and restore the access to the On-Premises Public Folders, by running:
Set-OrganizationConfig -PublicFoldersEnabled Remote -RemotePublicFolderMailboxes <YourOnPremisesPFMailbox>
This last change can take a while to apply. To make sure that the change applied, run the following cmdlet:
Get-Mailbox <username> |fl *public*
Once you are certain that the default Public Folder mailbox is the remote On-Premises one, inform the users that the access to the Public Folders has been restored. Again, this might take up to one hour, so plan carefully for the Public Folders downtime.
Finally, since the Organization Configuration on Office 365 has been changed, revisit the How do I enable Office 365 users to access legacy on-premises Public Folders? and run the script at the bottom to change the default public folder mailbox parameter to make sure that the MigrationWiz administrator on Office 365 has an Office 365 Public Folder mailbox as default.
Changing Primary Domain Type
Here are the steps to change the primary domain type in Office 365 from Authoritative to Internal Relay. These steps are important to follow when migrating Public Folders in hybrid mode.
- Log in to the Office 365 admin portal as a Global Admin.
- Launch Exchange Admin Center.
- Under Mail Flow, select Accepted Domains.
- Use the radio buttons to change the domain type. Choose Internal Relay: Email is delivered to recipients in this Exchange organization or relayed to an email server at another physical or logical location.
Here is a screenshot from the admin portal:
Note: There will be a warning about connectors. It is safe to dismiss this if you're only making this change to mail-enable your Public Folders.
Mail will now be successfully delivered.