On Premise Public Folder Migration to Public Folders in Exchange Online

Earlier this week, I spoke with Office 365 support regarding on premise public folder migrations to the new version of O365 Wave 15).  Based on what the engineer provided to me, the following is an “officially” supported migration path for migrating public folders in Exchange on-premise to public folders in Exchange Online.  Of course, there is no publicly accessible documentation for this procedure but I have tested these steps (in a lab environment) and it does work.  It is definitely not elegant though.


  • Identify/record which on-premise public folders need to be migrated
  • Identify/record permissions of each on-premise public folder
  • Create Public Folder mailbox in EAC of Exchange Online (or via PowerShell)
  • Create public folders with same structure as that on-premise and assign permissions (NOTE: This task can be performed via EAC, PowerShell or Outlook)
  • Export on-premise public folders to PST file via Outlook
  • Connect to Exchange Online mailbox via Outlook client to access public folders
  • Import public folder PST into Exchange Online public folder structure


  • Public Folders are not accessible or visible via Outlook Web App (OWA) in Exchange Online
  • Public Folders mailboxes are limited to 25GB total size
  • Additional Public Folder mailboxes seem to do nothing of value in Exchange Online
  • Public Folder mailboxes do not require a license


  • You must use Outlook 2007 or later to access public folders in Exchange Online


Best of luck.

 Todd (@oddytee)

Originally published on 20 March 2013 at http://oddytee.blogspot.com/2013/03/on-premise-public-folder-migration-to.html

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