For an Exchange 2016 migration, the public folder migration options depend on which version of Exchange you're migrating from:
- If you are migrating modern public folders from Exchange 2013 to Exchange 2016, you can simply move the public folder mailboxes just as you would migrate any other mailbox
- If you are migrating legacy public folders from Exchange 2010, then the process is more complicated
Keep in mind that if your organization has no need for legacy public folder data, you can simply remove your legacy public folders completely, instead of migrating them. If you later have a need for public folders, you can create modern public folders in Exchange 2016 at that time.
To migrate legacy public folders from Exchange 2010, a procedure called a batch migration is performed. At a high level the process involves:
- Downloading scripts from Microsoft
- Preparing the organization for public folder migration
- Generating CSV files using the Microsoft scripts
- Creating public folder mailboxes in Exchange 2016 databases
- Starting the migration, and waiting for initial synchronization to complete
- Locking the public folders for final migration (this requires an outage, usually of at least an hour, but longer for very large environments)
- Finalize the public folder migration
- Testing modern public folders, and then unlocking them for access by users (the outage is now over)
The public folder migration process is one-way only. Once you're using modern public folders, any changes or new data can't be synchronized back to the legacy public folder databases. This means that if you encounter a problem that requires you to roll back to your legacy public folders, you'll lose any new or changed data in the modern public folders (unless you take steps to back it up or copy it somewhere else). So from a risk management perspective, you should take the time to understand your public folder usage scenarios so that they can be tested thoroughly before a large amount of new data is generated in the modern public folders post-migration.
Microsoft maintains the most up to date guidance for legacy public folder migration to Exchange 2016 on TechNet, which you can find here. You can also see an example for migrating legacy public folders to Exchange 2013 here, which is an almost identical process.
After you've completed your public folder migration, you can begin decommissioning your legacy Exchange servers, which I'll cover in the final part of this series.