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Administrators' choices for Exchange 2016 public folders

Administrators who want to migrate public folders to Exchange 2016 should weigh the benefits over Exchange 2013 public folders and any migration risks before deciding.

Rumors of the death of public folders spread quickly several years ago, but today -- with some major changes --...

public folders remain widely used for collaboration and sharing information within enterprises.

Microsoft had planned to deemphasize Public Folders after Exchange 2007, and many administrators expected public folders to be removed entirely from on-premises Exchange Server. With the release of Exchange 2013, public folders got a new lease on life, and a new architecture based on public folder mailboxes instead of public folder databases. Modern public folders such as Exchange 2016 public folders -- as opposed to legacy public folders for versions prior to Exchange 2013 -- take advantage of the high availability and data redundancy of the database availability group.

Now that Exchange 2016 public folders are available to administrators, it's time to consider your options. Should you migrate public folders to Exchange 2016 or leave them where they are? And what about the cloud? There's a decision-making process to follow for migrating public folders to Exchange 2016.

Consider an Exchange 2016 public folder migration

Although Exchange 2016 is the latest version of Microsoft Exchange Server, it currently has the same public folder limits as the predecessor Exchange 2013. This means if you're migrating from legacy public folders, there is no scalability advantage to choosing Exchange 2016 over Exchange 2013.

Microsoft has laid out plans for both Exchange 2013 and 2016 to receive a "Lost and Found" feature to help with certain recovery scenarios for deleted public folder mailboxes in a future update.

If your future plans include migrating to Office 365, Microsoft provides a supported migration path from legacy public folders to modern public folders in Exchange Online, which runs Exchange 2016 behind the scenes. However, they do not currently have a supported migration path from on-premises modern public folders to Exchange Online. If a full cloud migration is on your roadmap, consider migrating the legacy public folders directly to Office 365, instead of creating on-premises Exchange 2016 public folders on a server.

If your future plans include migrating to Office 365, Microsoft provides a supported migration path from legacy public folders to modern public folders in Exchange Online, which runs Exchange 2016 behind the scenes.

All is not lost if you've already migrated your organization's public folders to Exchange 2016, then start planning to migrate to Office 365. A hybrid Exchange configuration will allow both on-premises and cloud mailbox users to access the on-premises public folders. You can continue to use existing public folders; however, you'll be maintaining the public folders on-premises until Microsoft provides a supported migration path to move them to the cloud.

One feature new to Exchange 2016 is the ability to perform In-Place eDiscovery and In-Place Hold for public folders. For organizations that have a need to search and preserve public folder data for legal matters, in-place discovery features strongly make the case for migrating public folders to Exchange 2016.

Migrating public folders to Exchange Server 2016

Migrating legacy public folders to Exchange Server 2016 has the same coexistence constraints as other aspects of the migration: Exchange Server 2016 can coexist with Exchange Server 2013 and 2010. If you have any Exchange 2007 or earlier servers in your organization, then you will need to migrate off those servers and decommission them before you can deploy the first Exchange 2016 server into the organization.

After you've made the decision to migrate public folders to Exchange 2016, the process takes seven steps.

  1. Perform a cleanup of the existing public folder data, or replace them with alternatives. For example, if users book meeting rooms or equipment via calendar public folders, replace those folders with resource mailboxes in Exchange. Cleaning up public folders is important if your organization approaches or exceeds the Exchange 2016 public folder limits. Even if you are not hitting those limits, removing unnecessary public folder data will be a good outcome for your organization.
  2. Complete your mailbox migration to Exchange 2016. Legacy mailbox users -- those on Exchange 2010 -- will not be able to access the modern public folders on Exchange 2016. This means the public folder migration is performed at the end of the migration project, or at least is performed only after all mailbox users who require public folder access have been migrated.
  3. Start the public folder migration. Microsoft publishes the batch migration steps on TechNet. These are the only supported steps for a public migration that Microsoft provides. The previously supported serial migration process has been deprecated and is no longer recommended.
  4. When the initial synchronization of public folder data has completed, schedule an outage window so you can lock the existing public folders, which will then be inaccessible to end users until you complete the migration.
  5. Complete the public folder migration batch, which will perform a final synchronization of any new or changed public folder data since the initial synchronization finished.
  6. Test the modern Exchange 2016 public folders using a test mailbox user in the organization. Tests should verify all of the public folders are present, permissions are intact, mail-enabled public folders are still configured correctly, and new folders and content can be created and deleted.
  7. If all of your tests pass, unlock the modern public folders so they will be accessible for end users.

Risks of public folder migrations

Legacy public folder migration to Exchange 2016 is a one-way process. If you encounter problems in your testing, or after the Exchange 2016 public folders have been live for some time, you can perform a rollback to the legacy public folders if they have not already been fully decommissioned. However, in doing so, you will lose any changes made to the public folder data after it was migrated to Exchange 2016.

The testing phase of the migration is very important, and also reinforces the value of cleaning up public folder data before migrating, to reduce the amount of data that needs to be tested and analysed after the migration.

Next Steps

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