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Public Folder Migration Guide From Hosted Exchange To Office 365 > 20GB

Last Update: 7/21/2017 11:32 AM
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​​​Public Folder Migration Guide From Hosted Exchange To Office 365 > 50GB

Important: When you sign in to MigrationWiz, you are redirected to the Getting Started page in MSPComplete. To get to a migration project created before April 4,​ 2017, click the Go to Projects button on the Getting Started Page. To create a new project for the migration scenario documented in this article, click the waffle icon (waffle.png) in the top navigation bar of MSPComplete, and select the appropriate migration product.


  • This is the complete Onboarding Task flow for migrating Public Folders from a multi-tenant Hosted Exchange environment running Exchange 2007 or later, to Public Folders on Office 365.
  • This guide should be followed if the total size of the public folders on the source is more than 20GB. If the public folders on the source are less than 20GB, refer to KB005116.
  • Complete each step in order. If additional instructions are required, a link to a corresponding Knowledge Base article is provided.
  • If you experience throttling limits when migrating to Office 365, and if you are migrating more than 1000 seats, you can increase throttling limits by following guidance provided in How to increase EWS throttling limits​.

Prepare Source Environment

  • Ensure that the migrating admin account has permission on all Public Folders (owner access rights need to be permitted to the account being used for migration). KB005103

    Note: You will 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.
  • When migrating from 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).

    This is the PowerShell script that your Hosted Exchange provider must run in order to obtain that PublicFolderRootEntryId:
    Get-PublicFolder "\the path of the 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).
  • 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. KB005526

Prepare Destination Environment

  • Set up the Office 365 tenant.
  • Add users and assign SKUs (if permissions are being migrated, this is required).
  • Create a Public Folder mailbox and assign root permissions to this Public Folder mailbox, to the admin account being used for the migration. Refer to KB005069 and KB004800.​
  • Allocate public folders from the source to their corresponding public folder mailboxes on Office 365 such that each mailbox on the destination remains below 20GB. 
    • Note: This is important because public folders that are larger than 20GB can automatically trigger automatic splitting of the public folder mailboxes on Office 365, which may cause the migration to fail.
    • Important: If any public folders at the source are greater than 20GB, you must break these down into folders that are smaller than 20GB. To do this, you must work with BitTitan support to restructure your public folder hierarchy using PowerShell scripts provided by BitTitan. Click here to contact BitTitan Support​.​
    • Note: This step can take several days to complete, so allow time for this in your project plan.

MSPComplete Steps

  • Create a customer. KB005421
  • Create the source and destination endpoints (select Exchange Server Public Folder  for the source endpoint, and Office 365 for the destination endpoint). KB005427
  • Launch public folder migration (select All Products > Public Folder Migration).​

MigrationWiz Steps

  • Set up Project (create a Public Folder project/Name the project and select the MSPComplete customer/Select the Source endpoint/Select the Destination endpoint).
  • If the Source Public Folders have more than 1000 folders below the top-level folder, work with BitTitan Support so that the migration can be split up, based on migration points after every 1000 folders. KB005239

    Note: Once the tool is complete, you must run the migration from the new project, and can then delete the original project.
  • Set Project Advanced Options KB004834
    • Set the value for Migrate Permissions For to New folder and existing folders. This is required because Public Folder mapping scripts have been created. KB004817
    • Under Licensing:
      • Set value for Maximum licenses to consume per item per pass licensing count.

        (Default value = 1. This allows up to 10GB to be migrated. For example: If migrating all Public Folders, using a forward slash ( / ), and the total data size = 39GB, increase this value to 4, otherwise the migration will pause at 10GB). KB004890
    • Under Performance:
      • Set Preferred BitTitan Data Center

        (For fastest migration speeds, select the Data Center that is closest to your Office 365 Destination tenant). KB004268
    • Under Support/Support Options, add:
      • RemoveFilterBasedOnFolderType=1

        (This flag is required if Public Folders contain items other than mail, such as calendar and contact items). KB005053
      • PublicFolderExportRootEntryId=xxxxxxxxxxxxxxxxxxxxx

        • The name of the Advanced Option is case-sensitive, and should be entered exactly as shown above.
        • The PublicFolderExportRootEntryId option should contain the EntryId of the Source top-level Public Folder.
        • Replace the "x"s with the ID that was obtained when running the PowerShell script provided in the "Prepare Source Environment" section of this Migration Guide.
        • After entering this text, click on the "+" sign to save the entry.
  • Import Public Folders into the dashboard.

    • Choose to migrate all Public Folders for customer, from the root down. Select Add/Quick Add and enter a forward slash ( / ) within the field labeled Root Folder Path. This is recommended, 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. This will then migrate all Public Folders, based on the PublicFolderRootEntryId that has been added into the project's Advanced Options. KB004914

    • Add individual Public Folders through Quick Add, and enter each root folder path.

      Note: You cannot use the Autodiscover option when migrating from Hosted Exchange environments. If Autodiscover is tried, it will time out, since it will attempt (unsuccessfully) to discover all Public Folders from the top-level root folder, which is protected.
  • Run Verify Credentials. KB004511
  • Purchase Public Folder licenses. KB004647
    • To obtain an estimate of the number of Public Folder migration licenses required for your migration project, follow the directions in KB005791.
  • First Pass MigrationWiz Steps:
    • Set first pass Project Advanced Options: KB005067
      • Add: MaintainWatermarkCompletionState=1
      • Set date to migrate items older than six (6) months.
  • Perform Full Migration pass (checkmark the box next to Root Path, select the Start button/select Full Migration from the drop-down list/click on the Start Migration button).
  • Second/Final Pass MigrationWiz Steps:
    • Set second pass Project Advanced Options: KB005067
      • Remove: MaintainWatermarkCompletionState=1
      • Add: SkipImportFolderWhenPublicFolderExists=1
      • Set the date to migrate items newer than six (6) months.
  • Perform Full Migration pass (put a checkmark in the box next to Root Path, select the Start button > select Full Migration from the drop-down list > click on the Start Migration button).
  • Perform a final Full Migration pass using the Advanced Option AllowAllMailboxTypesForPFPermissions=1 in order to migrate all Security Group Permissions. If you do not run the second pass, none of the Security Group Permissions will migrate.
  • Receive migration statistics (click on the pie chart on the MigrationWiz dashboard to receive an email containing all the project migration statistics). KB004626