Microsoft to Block Legacy Exchange Public Folder Migrations
Microsoft urges organizations to modernize Exchange environments before public folder migration support ends.
Key Takeaways:
- Microsoft will block native public folder migrations from Exchange Server 2010 or older in October.
- Organizations must act before the deadline or face a more complex, multi-step migration process.
- The move is part of Microsoft’s push to reduce reliance on legacy systems and enhance cloud security.
Microsoft is phasing out support for native public folder migrations from Exchange Server 2010 and earlier to Exchange Online. Organizations are being urged to complete their migrations before the October 2025 deadline to avoid service disruptions and added complexity.
The native public folder migration feature in Exchange Server 2010 is a built-in method to help organizations move their public folder data (including content, structure, and permissions) from on-premises Exchange environments to Exchange Online. This process involves using PowerShell scripts and migration batches to extract and transfer data while maintaining folder integrity.
The risks of sticking with outdated Exchange Servers
Starting on October 1, Microsoft will block all native public folder migrations from Exchange Server 2010 or earlier to Exchange Online. Any new migration jobs launched after this date will automatically fail. This move is intended to push organizations away from outdated Exchange systems, which pose greater security, compatibility, and performance risks.
“We are deprecating support for public folder migrations from Exchange Server 2010 and older versions to Exchange Online to reduce reliance on older systems and improve long-term service reliability. Public folder migrations from these on premises versions to Exchange Online (Public Folders and Microsoft 365 Groups) will be blocked starting October 1st, 2025. Public folder migration jobs will fail after this date,” the Exchange team explained.
How to prepare your organization before the deadline?
This change will affect organizations still running Exchange Server 2010 or earlier and planning to migrate public folders to Exchange Online using Microsoft’s native tools. Microsoft warns that after the cutoff date, these organizations will first need to upgrade to a newer Exchange version (such as 2016 or 2019) before they can move their data to the cloud.
Microsoft Exchange Server has been repeatedly targeted by cyberattacks exploiting previously unknown vulnerabilities. Due to the severity and persistence of these threats, Microsoft eventually shifted its strategy and introduced a subscription-only version of Exchange to ensure more consistent updates, tighter security controls, and better support for cloud-based environments.
Rabia has a master's degree in Software Engineering and she has years of experience writing professionally about Microsoft products and other technologies. Rabia has also written for OnMSFT.com as well as Windows Report. She is always up to date on t...