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 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
Shared mailboxes require delegated permissions for access to folders. Currently, MigrationWiz does not update the source Public Folder permissions to the destination Shared Mailbox delegated permissions. Our development team is working on the fix, until then the destination Shared Mailbox delegate permissions need to be applied manually.
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
- Public Folders and Subfolders
- Mail Folders
- Calendar Folders
- Contact Folders
- User Permissions (Folder level only)
- Mail-Enabled Security Group Permissions (Default and Anonymous User Permissions are not supported) - Folder level only
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
- Delegated permissions
Not Migrated in Exchange 2007: Public Folder Permissions
Modern Authentication Requirements
The steps listed in the Obtain Client and Tenant ID Settings for Mailbox and Exchange Online Migrations section of the Authentication Methods Migrations KB apply to both the source and destination tenant when they are Exchange Online, in regards to Exchange Web Services (EWS) in mailbox, archive mailbox, and public folder projects. Use a Global Administrator for the configuration steps.
Please review the documentation before preparing the environment.
Prepare the Source
- Grant admin permissions
- Break up large folders (if required)
Grant admin permissions
- Grant elevated 'Organization Management' administrator role to the migrating administrator account. Refer to Assigning the Elevated Admin Role 'Organization Management' to a Public Folder Account for Migration.
- 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.
- 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 Granting Necessary Permissions to Source Public Folders.
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 subfolders) 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
- 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.
- 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.
- 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 1.7 GB. These steps are from our article Microsoft 365 Public Folder Migration FAQ.
- Open a PowerShell session and enter the following. Then press Enter:
$LiveCred = Get-Credential
Install-Module -Name ExchangeOnlineManagement
Import-Module -Name ExchangeOnlineManagement
Connect-ExchangeOnline -ConnectionUri https://ps.outlook.com/powershell/ -Credential $LiveCred
- 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
- 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.
The following steps will be performed in MigrationWiz.
- Create project.
- Set endpoints.
- Add items.
- Run Verify Credentials.
- Purchase licenses.
- Set Advanced Options.
Create a Public Folder migration project. Read the MigrationWiz Projects article for more information on project types and troubleshooting.
- Click the Go to My Projects button.
- Click the Create Project button.
- Select Public Folder as the migration type.
- Click Next Step.
- Enter a Project name and select a Customer.
- Click Next Step.
Set the source and destination Endpoints (select Office 365 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.
When configuring the destination endpoint, do not forget to complete the client ID and the tenant ID fields for the Destination endpoint, otherwise, you cannot save your project migration.
Once the information has been provided for both, the source and/or destination endpoint and the customer selects Save and Go to Summary, MigrationWiz performs an endpoint validation check.
This validation tests the administrator credentials entered into the project and the Modern Authentication setup only. If there is an issue, the screen redirects to the endpoint and provides an error message or flyout that can be selected for more information regarding the error.
Common Errors when Configuring Your Endpoint
For more information, review the AADSTS700016, AADSTS90002, and ADDSTS50126 issues on the Common Errors Using Modern Authentication page.
Add the items you wish to migrate.
- Select Add.
- Select Quick Add.
- Enter a forward slash ( / ) in the Root Folder Path field.
- Add the address for the shared mailbox in the Destination Email 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 Migrating all Public Folders from the Root Level Down
If migrating specific public folders to multiple shared mailboxes, select Add > Bulk Add and enter the full path of each source folder to be migrated in the Root Path field and the address of the intended destination shared mailbox in the Destination Email field.
If migrating to multiple shared mailboxes, open a ticket with Support using the Subject “Public Folders to Shared Mailboxes: License Audit”. Include the Project name, the total GB of source Public folder data to be migrated, and the number of destination Shared Mailboxes being migrated to. This will allow Support to make sure that you have the correct number of licenses to migrate without having to purchase extras.
Now that your project has been created and/or added for the Root Path, or the specific folders to be migrated have been added, run Verify Credentials from the Start menu in the MigrationWiz project.
Purchase Public Folder licenses. To 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.
- 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.
- 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
- 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 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 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.
The client and tenant ID fields for the destination or source in the Support tab of the project’s Advanced Options may be view-only fields, this depends on the endpoint type you set before. This means that you cannot edit or remove them from the support options page. To edit them, you need to edit the project.
You cannot update the default Advanced Options, in case you try to modify or add new ones the following message arises.
- 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.
- Perform the first pass for items older than 6 months by running a Full Migration.
- Set second pass Project Advanced Options.
- Set the Date Filter to migrate items newer than six (6) months.
- Perform a second pass for items newer than 6 months by running a Full migration.
- Request the migration statistics. Click the bar chart icon on the MigrationWiz dashboard to receive an email containing all the project migration statistics.