Public Folder Migration Guide From On-Premises Exchange 2007+ to Office 365 (Hybrid Mode)


This is the complete onboarding task flow for migrating Public Folders from On-Premises Exchange 2010 SP1 or later, to Public Folders on Office 365, with a hybrid deployment.

We recommend reading through the complete guide before starting the migration. Complete each step in the order listed. If additional instructions are required, a link to a corresponding Knowledge Base article is provided.

To see what items are included in the migration, see Which Items Are Migrated by MigrationWiz?

MigrationWiz is not a sync tool. Items updated at the source mid-migration will not be updated at the destination.

MigrationWiz does not migrate SMTP addresses for mail-enabled Public Folders. They can be exported and imported using the scripts supplied here: Migrating mail-enabled Public Folder email addresses. Do not run the import script until the pre-synced mail-enabled Public Folder contacts have been removed from Office 365 (this is covered in the steps below). It is highly recommended that you review the path mail flow takes for entering your environment when mail is sent to mail enabled public folders and to ensure the items will be delivered to the mail-enabled folders in O365. MigrationWiz does not configure anything regarding mail flow and assisting with mail flow issues is beyond the scope BitTitan support can assist with.

MigrationWiz supports the capability to share migration projects across a Workgroup. When the Project Sharing feature is turned on, all Agents besides those who are Inactive can view all migration projects. For more information, visit Project Sharing in MigrationWiz.

We are not able to support migrations with two-factor or multifactor authentication. 

Prepare Destination Environment

  1. This guide presumes that your Office 365 tenant and users have already been created and licenses have been assigned to those users. It also presumes that the hybrid environment has already been set up between the On-Premises Exchange and Office 365 tenants. For instructions on setting up accounts and assigning licenses, see one of the articles below:
  2. The destination administrator account must have a valid Office 365 license assigned and an active mailbox in the Office 365 environment.
  3. Before giving Office 365 users access to the on-premises Public Folders, the first Public Folder mailbox in the Office 365 tenant will need to be created. This will be the Primary Hierarchy Public Folder mailbox. Do not name the primary mailbox the same as any public folder mailbox or database on the source on-premise Exchange server. A maintenance window may be needed for this step to reduce any downtime. For more information, see the Office 365 Public Folder Migration FAQ.
  4. Set users on Office 365 to access the on-premises Public Folders and configure the destination administrator account mailbox to access the Public Folders in Office 365. For more information, see How do I enable Office 365 users to access legacy on-premises Public Folders?
  5. Grant Owner permission to the destination administrator at the root (IPM_SUBTREE) of the Public Folder hierarchy. See How do I ensure the admin account being used for Public Folder migration has permissions on all Public Folders?

Important note: This guide presumes that mail-enabled Public Folders have been synced between the On-Premise Exchange server and Office 365 for mail flow purposes prior to migrating. These pre-synced, mail-enabled Public Folders will need to be removed from Office 365 BEFORE MigrationWiz can be used to mail-enable the physically migrated Public Folders in Office 365. The steps required for this are included in the MigrationWiz steps below. For more information, see How do I migrate mail-enabled Public Folders in hybrid mode?

Prepare Source Environment

  1. Grant elevated 'Organization Management' administrator role to the migrating administrator account. Refer to How do I assign the elevated admin role 'Organization Management' to the account that is performing a Public Folder migration?
  2. Ensure that the source administrator account has a mailbox enabled and is located on the same Exchange server as the source Public Folder database or mailbox.
  3. Ensure that the migrating administrator account has permission in all Public Folders (Read only or "Reviewer" access rights should be enough). For more information, see How do I ensure the admin account being used for Public Folder migration has permissions on all Public Folders?
  4. Split up large Public Folders: if any Public Folders contain more than 20,000 items (if Source = Exchange 2007), or 100,000 items (if Source = Exchange 2010 or later), these should be split into multiple Public Folders. This will speed up your migration. For more information, see How do I find the size of Source Public Folders? 
  5. Any individual Public Folders that are over 20GB in size should be split up into smaller folders of 20GB or less. Failure to complete this step can negatively impact migration performance and speed.

MigrationWiz Steps

  1. Set up the Public Folder migration project. Read the MigrationWiz Projects article for more information.
  2. Create the source and destination Endpoints (select Exchange Server Public Folder for the source Endpoint, and Office 365 Public Folder for the destination Endpoint). If your Destination endpoint is GCC High, select Office 365 Public Folders (US Government) for that endpoint. 
  3. Add Public Folders (select Add > Quick Add and enter a forward slash ( / ) in the Root Folder Path field.) We recommend this because it will migrate all Public Folders, and you will only need one Public Folder license per 10GB of data, regardless of the number of top-level Public Folders. Refer to How do I select to migrate all my Public Folders from the root level down? If targeting specific source folders for migration, contact BitTitan Support to add those specific folders to the project instead of the top-level Root folder.
  4. Run Verify Credentials. See Migration Process FAQ (Your migration project should be created and a successful Verify Credentials completed before moving on to the next steps).
  5. If migrating more than 1000 folders, you will need to work with BitTitan Support to split the migration up so that the project runs more efficiently.
    • First step: run this PowerShell command against your source environment:
      Get-PublicFolder -Recurse -Resultsize Unlimited | select Identity | Export-Csv -Encoding Unicode C:\folders.csv
    • This will generate a file called folders.csv. Once you have that CSV, follow these steps:
      • Open the CSV and remove the names of any folders that will not be included in the migration. After you have confirmed the folders listed in the folders.csv file are the ones to be migrated, attach the file to the ticket and indicate this step has been completed. Only folders included in the CSV will be included in the migration. Any new folders created after the Public Folder Split is initiated will not be included in the scope for the migration. For suggestions on working within this restriction, see Best Practices for migrating Public Folders.
      • If migrating more than 20GB, stop here and contact BitTitan Support.
        • When migrating more than 20GB of data, scripts will need to be created for the project by BitTitan Support to avoid the automatic Office 365 auto-split process for Public Folder Mailboxes. For more information, see How do I migrate more than 20GB of Public folder data to Office 365? If the total size of the migration is less than 20GB, these scripts are not required.
        • Open a ticket with BitTitan Support by following the instructions in How do I get support for your products?
          • If you already have a ticket open with BitTitan Support, this information can be added to the open ticket. The subject of the ticket should be “Public Folder Split and Foldermapping”
          • Once the MigrationWiz split process is complete, a new project will be created with “_SPLIT” in the title. You must run the migration from the new project.
        • After the Public Folder mappings scripts supplied by BitTitan support have been successfully run against the Office 365 tenant, we highly recommend performing the steps outlined under Office 365 as the destination in Best Practices for migrating Public Folders.
  6. Purchase Public Folder licensesTo obtain an estimate of the number of Public Folder migration licenses required for your migration project, follow the directions in How do I estimate the number of Public Folder migration licenses required?
  7. Perform the steps outlined under Office 365 as the destination in Best Practices for migrating Public Folders.
  8. Set Project Advanced Options. 
    • Under Source/Destination, set the value for Migrate Permissions For from New Folders Only to New folders and existing folders. This is required because Public Folder mapping scripts have been created. See How do I migrate Public Folder permissions?
    • Set value for Licensing/Maximum licenses to consume per item per pass licensing count. Default = 1. This allows up to 10GB to be migrated. Example: If migrating all Public Folders, using the forward slash ( / ), and the total data size = 78GB, then increase this value to 8 (otherwise the migration will pause at 10GB). See MigrationWiz Licenses.
    • Set your Preferred BitTitan Data Center. For fastest migration speeds, select the Data Center that is closest to your Office 365 destination tenant. Refer to MigrationWiz - General - FAQ.
    • Under Support Options add:
      • RemoveFilterBasedOnFolderType=1 This support option is required if Public Folders contain items other than mail, such as calendar and contact items. See How do I migrate a Public Folder with multiple item types?
        Note: This option stays in place for the entire migration process.
      • DoNotMailEnablePublicFolders=1 This support option is required and must remain until you are ready to mail-enable the migrated Public Folders after all data and permissions have been migrated. Note: This option must stay in place until you run the pass to mail-enable the migrated folders with step 16 later in this guide.
  9. Set first pass Project Advanced Options (this is to be considered your pre-stage pass).
  10. Perform first pass for items older than 6 months by running a full migration. 
  11. Set second pass Project Advanced Options.
    • Under Support Options:
      • Remove MaintainWatermarkCompletionState=1
      • Add SkipImportFolderWhenPublicFolderExists=1
    • Set the Date Filter to migrate items newer than six (6) months. 
  12. Perform a second pass for items newer than 6 months by running a full migration.
  13. Set Advanced Options for Security Group Permissions Pass.
    • Under Support Options:
      • Remove SkipImportFolderWhenPublicFolderExists=1
      • Add AllowAllMailboxTypesForPFPermissions=1
  14. Perform a Security Group Permissions pass by running a full migration. If you do not run this pass, none of the Security Group Permissions will migrate. For more information on Security Group permissions, see How do I allow Security Groups to be migrated during a Public Folder migration project?
  15. Disable all the mail-enabled Public Folders in the destination tenant. The steps can be found at the bottom of How do I migrate mail-enabled Public Folders in hybrid mode?
  16. Reset the items statistics for all line items in the project using the steps outlined in MigrationWiz Statistics & Statistics Lookup You will know the reset of items was successful if all migration data is blank or returned to 0.
    • Under Support Options:
      • Remove DoNotMailEnablePublicFolders=1
  17. Submit a full migration pass. This pass will mail-enable the migrated Public Folders in the destination tenant. When ALL line items show more than 0 bytes migrated in the project, that indicates the destination folders have completed being mail-enabled. (To make sure, you can always compare the number of mail-enabled folders between the source and destination.)
  18. After the migrated Public Folders have been mail-enabled in Office 365, you can use the scripts supplied here to export and import the SMTP addresses for them: Migrating mail-enabled Public Folder email addresses.
  19. If the mail-enabled Public Folders need to accept mail from external domains, you will need to run the following PowerShell command against the destination tenant. 
    Get-PublicFolder -Recurse -ResultSize Unlimited | ? {$_.MailEnabled -eq $True} | Add-PublicFolderClientPermission -User Anonymous -AccessRights CreateItems
  20. Change your primary domain type in Office 365 from Authoritative to Internal Relay for domains being used in mail-enabled Public Folder SMTP addresses. 
    Note: Without setting this, Office 365 bounces the message before it even checks whether a valid Public Folder address exists.
  21. Mail flow changes can take time to propagate through the new tenant. If, after an hour or two, mail flow to the mail-enabled Public Folders in the destination tenant is not working, you will need to contact Microsoft to assist you with resolving the mail flow issues. If mail is still being received by the mail-enabled Public Folders at the source, you can run another full migration pass to migrate those items over to the destination after mail flow issues are resolved.
  22. Cut over your users to point at the migrated Public Folders in Office 365 by running the following PowerShell command against the destination tenant.
    Set-OrganizationConfig -PublicFoldersEnabled Local -RemotePublicFolderMailboxes $null
  23. Request the migration statistics. Click the bar chart icon on the MigrationWiz dashboard to receive an email containing all the project migration statistics. 
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