Public Folder Migration Guide From On-Premises Exchange to Hosted Exchange


This is the complete Onboarding Task flow for migrating Public Folders from On-Premises Exchange 2007 or later to a multi-tenant Hosted Exchange environment.

  We recommend reading through the complete guide before starting the migration to understand the process, timeline, and prerequisites. You will see notes called out throughout the guide; pay attention to these, as they may provide information to avoid migration failure.

 Complete each step in the order listed. If additional instructions are required, a link to a corresponding Knowledge Base article is provided.

 BitTitan support does not offer post-migration guidance regarding the management and resolution of public folders on the source environment.

 Important: Mail-enabling of public folders is not supported for destination endpoints hosting On-Premise Exchange. 

 Due to a code defect in Exchange 2010, timestamps will not be preserved for Public Folders at the destination. 

 This migration is typically run in 3 migration passes to move over all selected items and security group permissions. (Migrating of permissions is only supported for Exchange 2010+).

 Public Folder migrations can take some time to properly configure endpoints. We recommend configuring the project endpoints a week or more before the migration to ensure they are ready for use.


 MigrationWiz is a migration tool, not a syncing tool. If changes are made at the source after migration, they will not sync to the destination, nor will changes made at the destination sync to the source. We do not have “live” monitoring of changes (as with a sync agent) and we cannot handle scenarios such as conflict resolution without user interaction.

 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. 

  Exchange Web Services (EWS) must be enabled in both the source and destination for this migration type 

What items are and are not migrated?

Public Folders can only be migrated to other public folders or shared mailboxes. We do not migrate Public Folders to individual user mailboxes or Microsoft 365 Group mailboxes or vice versa. Mail-enabled public folders are not supported for destination endpoints that are Exchange On-Premise and will need to be mail-enabled manually. For additional details about items that are and are not migrated from public folders, see our Migrated and Not Migrated Items article.

Exchange 2007


  • Public Folders
  • Subfolders

Exchange 2010 SP1+ & Microsoft 365


  • Public Folders
  • Subfolders
  • User Permissions
  • Mail-Enabled Security Group Permissions (Default and Anonymous User Permissions are not supported)

Not Migrated

  • Rules

Not Migrated in any Exchange Instance

  • Email templates
  • Email flags (if the destination is G Suite)
  • Safe Sender/Block Lists
  • Mail Settings
  • Standalone documents stored in Mailbox Folders or Public Folders (Example: IPM.Document item types)
  • System Public Folders
  • StickyNote folders

Not Migrated in Exchange 2007: Public Folder Permissions

Special Considerations For This Migration

If your migration involves more than 1,000 public folders, then there are additional steps that are required for a successful migration, and BitTitan Support will need to assist you. These steps are not required if your migration is smaller than that, and you may only require one or the other. Make sure you review these steps before beginning your migration.

Order of Operations

You must first successfully complete a Verify Credentials pass in your project before BitTitan Support can assist with these steps. Follow the steps starting at Prepare Source Environment through Run Verify Credentials below, then contact BitTitan Support. 

For Large Migration Projects

More than 1,000 folders (including sub-folders)

If migrating more than 1,000 folders in total (including sub-folders), the folders will need to be SPLIT into multiple line items in your MigrationWiz project. This process increases the efficiency of the migration in case there are specific folders that may cause issues during the migration, and to allow folders to be migrated in parallel line items instead of a single one. If you are migrating less than 1,000 folders for the project, this steps is not required.

    • First, run the following PowerShell command against your source Exchange server. This will generate a file called folders.csv that will be used to create the SPLIT project.
      Get-PublicFolder -Recurse -Resultsize Unlimited | select Identity | Export-Csv -Encoding Unicode C:\folders.csv
    • Once you have that CSV, follow these steps:
      • Open the folders.csv file and remove the folder paths for any folders that should not be included in the migration. After you have confirmed the folder paths listed in the folders.csv file are the ones to be migrated, save the file (do not change the encoding) and attach the file to the ticket and indicate this step has been completed. 
      • Once the folders.csv file has been used to create a secondary SPLIT project (it will have _SPLIT included in the name), this will be the project used to migrate your public folders moving forward.

SPLIT Folder Paths

Only folder paths present in the folders.csv file used to create the SPLIT project will be migrated. Any new folders added at the source after the creation of the SPLIT project will need to be manually added after. For suggestions on working within this restriction, see Best Practices for migrating Public Folders.

Open a ticket with BitTitan Support

Once you have completed the Run Verify Credentials step, open a ticket with BitTitan Support by following the instructions in How do I get support for your products? Make sure to include the following information in your ticket:

  • The subject of the ticket should be “Public Folder SPLIT or Mapping Scripts Needed”
  • Make sure to attach the folders.csv file to the ticket from the step above for migrating more than 1,000 folders if one is required.

If you have already submitted a ticket for another issue, simply add the new information to that existing ticket.

Prepare the Source

  1. Grant admin permissions
  2. Ensure that the source administrator account has a mailbox enabled.
  3. Break up large folders (if required)

Grant admin permissions

Break up large folders

You will want to perform these tasks before beginning your migration. If you are migrating more than 1,000 folders (including sub folders) and/or more than 20GB of data, break these folders up before contacting BitTitan Support.

  • Split up large Public Folders: if any source Public Folders contain more than 100,000 items (if Source = O365, Exchange 2010 or later), these should be split into multiple Public Folders as they can cause migrations to be held up with processing of the high number of items. Breaking up these folders can help with faster migration speeds. For more information, see Finding Public Folder Size for Migration
  • 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.

Prepare Destination

  1. Create a single top-level Public Folder on the destination that your public folder hierarchy will be migrated to. Do not create subfolders. Let MigrationWiz create these during the migration, so that permissions get migrated over.
  2. Ensure the migrating administrator account has permissions applied on the top-level folder created at the destination.
  3. Run PowerShell commands.
    Note:You will most likely not be able to run the PowerShell commands on your Hosted Exchange environment. Ask the Hosted Exchange provider to add this permission to the account that is being used for migration. If they do not want to provide "owner" access rights, ask them to add "read" access rights instead.

PowerShell Commands

When migrating to a multi-tenant Hosted Exchange environment, the Public Folder structure on that hosted environment is under a top-level Public Folder, and not under the root folder. Additionally, the Hosted Exchange provider will not grant access to the root of their Public Folders, since this is a shared environment. Therefore, ask the provider to run the PowerShell script below so that we can obtain the unique identifier for the customer's top-level Public Folder. Then add that to the MigrationWiz project, under Advanced Options (this step is included in the MigrationWiz section below).

Get-PublicFolder "\the path of the destination top-level PF" | fl entryid*

Note: Record the output of this script. This needs to be entered under the MigrationWiz project's Advanced Options (as indicated in the MigrationWiz Steps section below).

MigrationWiz Steps

The following steps will be performed in MigrationWiz.

  1. Create project
  2. Create endpoints
  3. Add items
  4. Run Verify Credentials
  5. Purchase licenses
  6. Set Advanced Options
1. Create project 2. Set endpoints 3. Add items 4. Run Verify Credentials

Create a Public Folder migration project. Read the MigrationWiz Projects article for more information on project types and troubleshooting.

  1. Click the Go to My Projects button.
  2. Click the Create Project button.
  3. Select Public Folder as the migration type.
  4. Click Next Step.
  5. Enter a Project name and select a Customer.
  6. Click Next Step.

Purchase licenses

Purchase Public Folder licensesTo obtain an estimate of the number of Public Folder migration licenses required for your migration project, follow the directions in Estimating the Required Public Folder Migration License Count.

Set Advanced Options


The advanced option steps listed below should be followed in the order that they are entered as they are required for this migration scenario.

  1. 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 Migrating Public Folder Permissions
  2. 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.
  3. Set your Preferred BitTitan Data Center. For the most optimum migration speeds, select the Data Center that is closest to your Microsoft 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. 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 folders, files and permissions have been migrated. This option must stay in place until you run the pass to mail-enable the migrated folders with step 3 under Mail Enabling Your Migrated Public Folders later in this guide.
  • PublicFolderExportRootEntryId=xxxxxxxxxxxxxxxxxxxxx (This is the entry id of the top-level folder at the source)
  • PublicFolderImportRootEntryId=xxxxxxxxxxxxxxxxxxxxx (This is the entry id of the top-level folder manually created at the destination)
    • These options stay in place for the entire migration process.
    • The PublicFolderExportRootEntryId option should contain the EntryId of the source top-level Public Folder.
    • The PublicFolderImportRootEntryId option should contain the EntryId of the destination top-level Public Folder.
    • The names of the support options are case-sensitive and should be entered exactly as shown above.
    • Replace the "x"s with the ID that was obtained when running the PowerShell scripts provided in the "Prepare Source Environment" and "Prepare Destination Environment" sections of this Migration Guide.
  • After entering each support option, click the "+" sign to save the entry, and then add the next entry in the available field.

Perform Migration

You will now begin your migration. This will occur in multiple phases. Each migration pass has additional required advanced options and will be submitted as a Full Migration. Each pass must be completed successfully before moving on to the next migration pass.

  1. First migration pass
  2. Second migration pass
  3. Security group permissions migration pass

The advanced options detailed in the migration steps in the tabs below are intended to help increase the speed of your migration. For additional details on these options, please view our FAQ article here.

1. First pass 2. Second pass 3. Security group permissions pass 

First Migration Pass Steps

The first migration for this scenario usually takes more time to complete than the subsequent passes, and completes the following tasks:

  • Folder and file/item discovery
  • Migrate user folder permissions if a match can be found. For more information on the requirements for migrating user permissions, see Migrating Public Folder Permissions

Additional advanced options

Set first pass Project Advanced Options (this is considered your pre-stage pass as the older items will be migrated first).

Under Support Options add:

      • MaintainWatermarkCompletionState=1 

Under Filtering:

      1. Select By Date
      2. Check box Only migrate items older than the specified date
      3. Set date range (month, day, hour, minute) for items to migrate. We suggest migrating items older than six months. Dates will be calculated by the most recent modification date.

Perform the first migration pass

      1. Perform first pass for items older than 6 months by running a Full Migration from the Start menu. 


  • After the migrated Public Folders have been mail-enabled in the destination, you can use the scripts supplied here to export and import the SMTP addresses for them: Migrating mail-enabled Public Folder email addresses.
  • 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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