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.
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
- 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
The two options listed below apply to both the source and/or destination tenant when they are Exchange Online, in regards to Exchange Web Services (EWS) in mailbox, archive mailbox, and public folder projects. Select the option you wish to use for either your source or destination tenant. Use a Global Administrator for the configuration steps.
Important: Failure to perform the steps for one of the two required options for your Microsoft 365 endpoints, can result in failed jobs with 401 errors like the following in your project: Http POST request to 'autodiscover-s.outlook.com' failed - 401 Unauthorized
Regardless of the option selected, the administrator account being used for the project needs to be excluded from any MFA/2FA policies or Conditional Access policies that can block access for the administrator account. This requirement does not apply to the items or users being migrated in the project.
Of the two options available, the more recommended is the Modern Authentication option, as it is more secure. Configuring Modern Authentication to work with MigrationWiz and Exchange Online will be the default method by end of December 2022 due to Microsoft discontinuing support for Basic Authentication in Exchange Online. The following Microsoft documentation outlines this change in more detail. Should you have additional questions on how this change may impact your tenant, please contact Microsoft to assist with providing that information: Deprecation of Basic authentication in Exchange Online
Regardless of the option selected, the Azure Security Defaults must also be disabled in the tenant. (This is often enabled by default for all new Exchange Online tenants and there is no workaround for this requirement). For steps on where to enable/disable the Azure Security Defaults, see Enabling security defaults in the following Microsoft documentation. To disable, set Enable Security defaults to No: Security defaults in Azure AD
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 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
- 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 1.7GB. These steps are from our article Microsoft 365 Public Folder Migration FAQ.
- 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
- 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.
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 / 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 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.
- 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 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.