Best Practices for migrating Public Folders

The following steps are recommended before migrating to help reduce the number of errors or delays you might experience in your Public Folder migration.

When your project is split by BitTitan Support

  • If there has been a SPLIT created for your project due to migrating more than 1000 folders, as per our article How do I split migrations based on child Public Folder count?, any new folders created on the source after the SPLIT has been created will NOT be included in the migration. It is recommended that you perform one of the following, as doing so will save you time, especially during longer migrations:
    1. Block the ability to create new folders at the source.
    2. Create a single top-level folder at the source and require that all new folders be created under that single folder. Once the migration is closer to completion, the name of that top-level folder can be added to the project as its own Root Path and migrated. Once the folder has finished migrating, the end users can then move their folders to their intended parent folders.

Exchange as the Source or Destination

If the source or destination is Exchange 2010+, disable throttling for the administrator account being used for the migration using the following steps:
Note: The following steps are taken from our article How do I disable the throttling policy on Exchange?

Exchange Server 2010

  • To disable all throttling parameters for an admin account called "MigrationWiz":
    1. On a computer that hosts the Microsoft Exchange Management Shell, open the Microsoft Exchange Management Shell.
    2. Type the following command and press Enter:
      New-ThrottlingPolicy MigrationWizPolicy
    3. Type the following command and press Enter:
      Set-ThrottlingPolicy MigrationWizPolicy -RCAMaxConcurrency $null -RCAPercentTimeInAD $null -RCAPercentTimeInCAS $null -RCAPercentTimeInMailboxRPC $null -EWSMaxConcurrency $null -EWSPercentTimeInAD $null -EWSPercentTimeInCAS $null -EWSPercentTimeInMailboxRPC $null -EWSMaxSubscriptions $null -EWSFastSearchTimeoutInSeconds $null -EWSFindCountLimit $null -CPAMaxConcurrency $null -CPAPercentTimeInCAS $null -CPAPercentTimeInMailboxRPC $null -CPUStartPercent $null
    4. Type the following command and press Enter:
      Set-Mailbox "MigrationWiz" -ThrottlingPolicy MigrationWizPolicy

Exchange Server 2013 or 2016

  • To disable all throttling parameters for an admin account called "MigrationWiz":
    1. Open the Exchange Management Shell.
    2. Type the following command and press Enter:
      New-ThrottlingPolicy MigrationWizPolicy
    3. Type the following command and press Enter:
      Set-ThrottlingPolicy MigrationWizPolicy -RCAMaxConcurrency Unlimited -EWSMaxConcurrency Unlimited -EWSMaxSubscriptions Unlimited -CPAMaxConcurrency Unlimited -EwsCutoffBalance Unlimited -EwsMaxBurst Unlimited -EwsRechargeRate Unlimited
    4. Type the following command and press Enter:
      Set-Mailbox "MigrationWiz" -ThrottlingPolicy MigrationWizPolicy

Office 365 as the Destination

Increase the public folder quotas to Unlimited. The default Office 365 Public Folder quota setting is 2GB, with the issue warning set to 1.7GB. These steps are from our article How do I check what my Public Folder quotas are set to, and increase the quota size?

  • Run the following PowerShell commands against the destination tenant. (Note: After you apply these settings, wait at least 30 minutes before you start the migration.)
    1. Open up 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 public folder limits:
      Get-OrganizationConfig | fl *DefaultPublicFolder*
    3. Enter the following command and press Enter. This will set the new quota and issue warning quota to Unlimited:
      Set-OrganizationConfig -DefaultPublicFolderProhibitPostQuota Unlimited -DefaultPublicFolderIssueWarningQuota Unlimited
  • Note: The public folder mailboxes must exist before this can be set. These steps can be found in our article How do I migrate large mail items to Office 365?
    1. Open up 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 150MB
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