As a first step, you need to analyze the overall size of public folders that are planned to be migrated to Exchange organization. This can be done by reviewing information in Exchange System Manager (applicable to Exchange 2003) or by invoking theGet-PublicFolderStatistics cmdlet (applicable for Exchange 2007 or 2010).
This document contains information on one-way public folder synchronization using legacy agents in migration scenarios from Microsoft Exchange 2010/2013/2016 to Microsoft Office 365. In case you prefer alternative method of one-way public folders synchronization by enhanced Migration Agent for Exchange (MAgE) combined with extended MMEx PowerShell module refer to Public Folder Synchronization (MAgE) document. This synchronization method does not currently have an appropriate user interface and is intended for advanced PowerShell users only.
Prior to actual public folder migration, you need to plan how public folders should be migrated:
NOTE: If you migrate form Exchange 2007 or 2010, you can use the Export-PublicFolderStatistics.ps1 script to identify public folder sizes. That script creates file with public folders names and their sizes. For more information, see this TechNet article.
Now you can actually migrate public folders according to your migration plan by taking the following steps:
For more information, review information in the Sample Migration Scenario section that describes a real-world example of migrating large public folders to Exchange 2013.
Q: How agents match public folders?
A: Generally, agents match public folders by the folder’s PR_SOURCE_KEY. However if the public folder selected in public folder collection as a target root public folder already exists in the target organization, then its PR_SOURCE_KEY will not be the same as PR_SOURCE_KEY of the corresponding source root public folder. PFSA and PFTA store matching information for such public folders in their Config.mdb databases.
Q: Is it possible to move public folder between public folder mailboxes in Exchange 2013 or higher organization after synchronization begins?
A: Yes, public folder created by PFTA in Exchange 2013 organization can be moved to another public folder mailbox using New-PublicFolderMoveRequest. That does not require change of synchronization settings for public folders. This approach is useful if after you start synchronizing public folders, you reveal that there is not enough space for public folder content in a certain target public folder mailbox.