[German]I am posting some information here in the blog that Microsoft published some time ago. Microsoft has definitively discontinued the feature for migrating folders from ancient Exchange Server versions prior to Exchange 2013 to Exchange Online. From October 1, 2025, data from such legacy systems will no longer be able to be migrated.
Exchange Server Microsoft has long ended support for versions older than Exchange 2016. Even support for Microsoft's Exchange Server 2016 and Exchange Server 2019 will end on October 14, 2025. However, there were and still are customers who are running Exchange Server versions older than 2016 and suddenly find that support is no longer available. Until now, these customers have been able to transfer/migrate their data from these older versions of Exchange (Exchange 2013 or older) to Exchange Online using the migration tools developed by Microsoft..
The Exchange team already announced the discontinuation of this feature at the end of July 2025 in the Techcommunity post Deprecation of native public folder migrations to service from very old versions of Exchange. Microsoft is discontinuing support for migrating public folders from Exchange Server 2010 and earlier versions to Exchange Online. This is intended to reduce dependence on older systems and improve the long-term reliability of the service.
Starting October 1, 2025, migration of public folders from these on-premises versions to Exchange Online (public folders and Microsoft 365 groups) will be blocked. This means that public folder migrations from legacy systems will fail after this date.
Companies that currently use Exchange Server 2010 or older versions and plan to migrate public folders to Exchange Online (public folders and Microsoft 365 groups) using Microsoft's native migration tools should complete this migration by the deadline.
The question is how many systems this actually affects, as Exchange Server 2010 and older versions have been out of support for many years. Even Exchange Server 2013, whose folder migration is still supported, has long since ceased to be supported. From November 2025, all customers running on-premises Exchange Server must have switched to Microsoft Exchange Server Subscription Edition (SE).
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Exchange Server 2016 / 2019 reach their EOL in October 2025
Microsoft on the "decommissioning"; of Microsoft Exchange 2016
Exchange Server Subscription Edition (SE) release (July 1, 2025)
