Starting October 1, 2025, Microsoft will no longer support public folder migrations from Exchange Server 2010 and older versions to Exchange Online using its own migration tools.
Organizations still using Exchange Server 2010 or older versions and planning to migrate their public folders to Exchange Online can do so until September 30, 2025. After that, all migration attempts with Microsoft’s native tools will automatically fail. The change applies to migrations to both Public Folders and Microsoft 365 Groups in Exchange Online.
Microsoft states that the decision aims to reduce reliance on outdated systems and improve the long-term reliability of its cloud services. Those wishing to transfer public folders from Exchange 2010 or older to Exchange Online after the deadline will first need to upgrade to a more recent version of Exchange Server, such as 2016 or 2019.
Extremely Outdated
Although Microsoft has long ceased support for Exchange Server 2013 and older versions, migrations from those systems to Exchange Online have so far been allowed via standard migration tools. This will now end for Exchange 2010 and older.
Support for Exchange 2010 ended in 2020. Microsoft has since provided a migration path five years after the end of support. To put that in perspective: Exchange 2010 itself enjoyed ten years of official support.
The fact that migration is now becoming more complex can be inconvenient. On the other hand, it raises the question of how much responsibility still lies with Microsoft to provide such functionality. With the historical vulnerabilities of Exchange on-premises and the massive hack in 2021, there was ample reason to plan a migration. Those still using Exchange 2010 five years after the end of support and fifteen years after its introduction bear a significant responsibility themselves.