Exchange or Microsoft 365 Public Folder to Exchange or Microsoft 365 Shared Mailbox Migration Guide

Introduction

This is the complete onboarding task flow for migrating public folders from Exchange 2007+ or Microsoft 365 to shared mailboxes in Exchange 2010+ or Microsoft 365. This document will walk you through the environment preparation and MigrationWiz steps necessary to perform your migration.

  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.

MigrationWiz


 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. 

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 2010 SP1+ & Microsoft 365

Migrated

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

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

Prepare the Source

  1. Grant admin permissions
  2. Break up large folders (if required)

Grant admin permissions

Break up large folders

You will want to perform these tasks first 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 the Destination

  1. Use a global administrator account for the tenant. This can be an already created account or can be created specifically for this migration. The administrator account being used for the migration must have a licensed mailbox enabled in the tenant.
  2. Create the shared mailboxes and grant the destination administrator account Full Access permissions to the shared mailboxes. The steps to create these are defined in a TechNet article here.
  3. If the destination is Microsoft 365, increase the shared mailboxes maxsend and maxreceive size to 150MB. If the destination is Exchange, increase the message size limits.

Increase message size limits

Increase the public folder quotas to Unlimited. The default Microsoft 365 Public Folder quota setting is 2GB, with the issue warning set to 1.7GB. These steps are from our article Microsoft 365 Public Folder Migration FAQ.

  1. Open a PowerShell session and enter the following. Then press Enter:
    $UserCredential = Get-Credential
    $Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential
    $UserCredential -Authentication Basic -AllowRedirection
    Import-PSSession $Session
  2. Enter the following command and press Enter. This will show you the current limits set on the public folder mailboxes:
    Get-Mailbox -PublicFolder | fl Name,MaxSendSize,MaxSendSize
  3. Enter the following command and press Enter. This will increase the MaxSendSize and MaxReceiveSize to the maximum allowed limits. (If there are items at the source that are larger than 150 MB, they will not migrate.)
    Get-Mailbox -PublicFolder | Set-Mailbox -PublicFolder -MaxReceiveSize 150MB -MaxSendSize 150MBAdditional details about send and receive size limits can be found in our Best Practices for Migrating On-Premises Exchange Public Folders article.

MigrationWiz Steps

The following steps will be performed in MigrationWiz.

  1. Create project
  2. Set 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

Important 

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. Select the option for Migrate to: Shared Mailbox. This will be found under either Destination: Exchange Server 2007+ or Destination: Microsoft Office 365, depending on what was selected when creating the destination endpoint.
  2. 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
  3. 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.
  4. 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.
  • MustMigrateAllPermissions=1 This flag is required in order to migrate Public Folder permissions to a shared mailbox. This Advanced Option allows you to migrate all folder permissions, not only the system folders when migrating from Exchange 2010+ mailboxes as, by default, only systems folder permissions are migrated. We do not migrate Delegation, SendAs/SendOnBehalfOf permissions or any permissions for the Default or Anonymous user accounts. For more information, see Migrating Public Folders to Shared Mailboxes.
     Note: This option stays in place for the entire migration process.

Run Migration

  1. Set first pass Project Advanced Options. For more information on running multiple passes, see Pre-Stage vs. Big Bang Strategy for Public Folders.
    • Set Date Filter to migrate items older than six (6) months. Date range filters can be set under Advanced Options.
  2. Perform first pass for items older than 6 months by running a Full Migration. 
  3. Set second pass Project Advanced Options.
    • Set the Date Filter to migrate items newer than six (6) months. 
  4. Perform a second pass for items newer than 6 months by running a Full migration.
  5. 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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