How to Migrate Exchange 2019 Public Folders to Office 365?

Migrating mailboxes from on-premises Exchange Server to Office 365 is easy and straightforward. However, when it comes to migrating public folders, the process is relatively complex and time-consuming as involves a set of scripts and procedures that require a lot of preparation work and resources. In this post, we will be explaining the stepwise process to migrate Exchange 2019 public folders to Office 365.

Process to Migrate Exchange 2019 Public Folders to Office 365

Here’s the step-by-step process to migrate public folders from Exchange Server 2019 to Office 365.

1. Fulfil the Prerequisites

Before starting the migration, you need to ensure the following:

• The traffic between the server and the internet is open and there are no bandwidth restrictions.
• The Exchange Server and the underlying operating system are updated.
• There are no scanning or backup jobs running during the migration.
• The Active Directory is prepared if you have the Exchange Server 2019 migrated from an Exchange Server 2013 or 2016.
• The user performing the operation must be a member of the Organization Management Role Group on the local Exchange Server and Exchange Online.

In addition, here are some considerations you need to keep in mind:

• There is a limitation of 1000 public folder mailboxes in Office 365.
• MRS proxy is required and must be enabled on Exchange Server 2019.
• Migration can be done and executed from the Exchange Management Shell (EMS).
• The migration batch cannot have multiple migration batches running simultaneously.
• The user performing the migration cannot have the Multi-Function Authentication (MFA) enabled.
• Each public folder cannot exceed the 25 GB size limit.

2. Download the Scripts

To start the migration process, you need to first download the migration scripts from the Microsoft website.

Then, extract the files into C:\Scripts\PFMigration or any folder of your choice.

3. Create the Accepted Domain

Now, you need to add the Office 365 domain as an accepted domain in the local Exchange Server.

New-AcceptedDomain -Name PublicFolderMigration -DomainName mycompany.onmicrosoft.com

4. Clean Up Process

The next step is to clean up the local public folders from unnecessary data, run a retention process, and take a backup of the public folders. This will ensure that the migration will be faster and that only the needed data is migrated.

You need to remove any started, completed, or locked public folder migrations and any listed public folder migration requests. To do so, use the below command:

Get-PublicFolder -Recurse -ResultSize Unlimited | Where {$_.Name -like "*\*" -or $_.Name -like "*/*"} | Format-List Name, Identity

5. Remove any Locks on Public Folders

You need to also remove any migration locks on the public folders. For this, run the below command:

Set-OrganizationConfig -PublicFoldersLockedforMigration:$false -PublicFolderMigrationComplete:$false -PublicFolderMailboxesLockedForNewConnections:$false -PublicFolderMailboxesMigrationComplete:$false

6. Get the Local Public Folders Statistics

Now, you need to get the local public folder statistics. From the downloaded scripts, you can run the Export-PublicFolderStatistics.ps1 command to get the results (see the example below).

7. Generate the Source to Destination Mapping File

You need to run the PublicFolderToMailboxMapGenerator.ps1 to generate the mapping file.

8. Create Empty Public Folders in Office 365

Next, you need to run the script to create the local public folders, from the files you created, into the Exchange Online. For this, use the Create-PublicFolderMailboxesForMigration.ps1 file. When executing this command, you will be asked to enter the Global Admin of your Exchange Online.

.\Create-PublicFolderMailboxesForMigration.ps1 -FolderMappingCsv pfef.csv -EstimatedNumberOfConcurrentUsers:<estimate number>

9. Start the Synchronization

After creating the local folders in Exchange Online, you need to synchronize the data from the local server to the cloud.

To synchronize the mail-enabled folders, you can run the following command:

.\Sync-MailPublicFolders.ps1 -Credential (Get-Credential) -CsvSummaryFile:log.csv

10. Add Local Credentials and URLs

Next, you need to add the local credentials. To do so, execute the below command:

$Source_Credential = Get-Credential <MyDomain\MyPublicFolderAdministrator>

To input the Outlook Anywhere URL for the server, Remote Public Folder DNS, and the Remote Mailbox legacy DN, you can run the below commands:

$Source_OutlookAnywhereExternalHostName = "<URL>"

$Source_RemotePublicFolderServerLegacyDN = "<URL>"

$Source_RemoteMailboxLegacyDN = "<URL>"

11. Create the Migration Batch

Once this is complete, you need to create the migration batch. For this, run the following command:

$PfEndpoint = New-MigrationEndpoint -PublicFolder -Name PublicFolderEndpoint -RPCProxyServer $Source_OutlookAnywhereExternalHostName -Credentials $Source_Credential -SourceMailboxLegacyDN $Source_RemoteMailboxLegacyDN -PublicFolderDatabaseServerLegacyDN $Source_RemotePublicFolderServerLegacyDN -Authentication Basic

[byte[]]$bytes = Get-Content -Encoding Byte <folder_mapping.csv>

New-MigrationBatch -Name PublicFolderMigration -CSVData $bytes -SourceEndpoint $PfEndpoint.Identity -NotificationEmails <email addresses for migration notifications>

Then, run the Start-MigrationBatch command as given below.

Start-MigrationBatch <migration batch name>

You can confirm the status of the migration batch in the Exchange Admin Center (Online). When the Status is Synced, you can start the cutover and close the migration.

12. Close the Migration

Before closing the migration, you need to run last synchronization to take the changes from the seeding. Here’s the command to do so:

Complete-MigrationBatch PublicFolderMigration

Once this is done, you can decommission the local public folders.

Set-OrganizationConfig -PublicFoldersLockedForMigration:$true

Set-OrganizationConfig -PublicFolderMigrationComplete:$true

An Alternative Solution for Migrating Public Folders to Office 365

As you can see, the above process of migrating public folders from on-premises Exchange Server to Exchange Online is not that intuitive and needs some skills and expertise to successfully complete the migration process. To make the migration process easier and smoother, you can use a specialized third-party EDB converter tool, such as Stellar Converter for EDB. This tool can help you to migrate user mailboxes, shared mailboxes, user archives, disabled mailboxes, and public folders to PST and other file formats. It can also migrate the EDB data, including public folders, directly to Exchange Online (Office 365) and a live Exchange Server database.

Conclusion

In Exchange Server, public folders are used to store important data related to organization. When migrating to Office 365, you need to also migrate the public folders separately. Above, we have discussed the stepwise process to help you with the Exchange 2019 public folders to Office 365 migration. However, the manual process is quite lengthy, tedious, and time-consuming. To simplify and ease the migration process, you can use a third-party EDB converter tool, such as Stellar Converter for EDB. This tool can help you migrate public folders and other data from Exchange Server EDB file to Office 365 in just a few simple steps.