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Microsoft Outlines How To Move Public Folders to Exchange Online

• By Kurt Mackie
• 03/21/2017

Documents by Microsoft showing how to move move public folders from Exchange Server 2013 or Exchange Server 2016 to Exchange Online were published online this week.

Public folders are used to share information in an organization. Moving them to Exchange Online was something that customers had requested, and now Microsoft has documented the steps. To migrate public folders, organizations need to assure that Exchange 2013 is already running Cumulative Update 15 or later versions, while Exchange 2016 needs to be updated to be running Cumulative Update 4 or later versions, per Microsoft's announcement.

The documentation for Exchange 2013 public folder migrations is located here. Documentation for Exchange 2016 can be found at this page.

Unfortunately, moving public folders from on-premises Exchange Server environments to Exchange Online in Microsoft's datacenters is not a simple wizard-driven process. The migration requires initial steps, such as preparing Active Directory and permanently removing deleted folders. Folders sizes need to be checked before the move since public folders have a 25-GB limit on Exchange Online. There's also a limit of "1,000 public folder mailboxes" on Exchange Online.

Users can't carry out the migration using the Exchange Admin Center console. Instead, for Exchange 2013, the Exchange Management Shell has to be used. There's also work to be done on Exchange Online, which requires using Exchange Online PowerShell. Microsoft provides a bunch of scripts for the various migration steps.

There's some downtime for public folder access during the final synchronization stage with Exchange Online. The last stage, after migrating the public folders, involves deleting the ones located on premises. However, it's a permanent deletion and can't be undone, according to the documentation.