Microsoft has announced a significant policy change affecting organizations using legacy versions of Exchange Server. Starting October 1, 2025, the company will block native public folder migrations from Exchange Server 2010 and earlier to Exchange Online. This move is part of Microsoft's ongoing efforts to enhance cloud security and reduce reliance on outdated systems.
Public folders have long been a staple in Exchange Server, providing a shared space for users to collect, organize, and share information within an organization. Traditionally, migrating these folders to Exchange Online involved using built-in tools and PowerShell scripts to transfer data while preserving the folder hierarchy and permissions. However, with the upcoming deprecation, organizations still operating on Exchange Server 2010 or older will face new challenges.
After the October 1, 2025 deadline, any new migration jobs initiated from these legacy servers will automatically fail. To migrate public folders to Exchange Online post-deadline, organizations will first need to upgrade to a newer version of Exchange Server, such as 2016 or 2019, before proceeding with the migration. This additional step introduces more complexity and potential downtime, emphasizing the importance of acting before the cutoff date.
The decision to block these migrations stems from several factors. Older Exchange servers, particularly those no longer supported by Microsoft, pose significant security risks. They are more susceptible to vulnerabilities and lack the robust security features present in newer versions. By encouraging organizations to move away from these outdated systems, Microsoft aims to improve overall service reliability and security.
For organizations currently using Exchange Server 2010 or earlier, the recommended course of action is clear: complete public folder migrations to Exchange Online before October 1, 2025. This proactive approach will help avoid the complexities associated with upgrading to a newer Exchange version solely for migration purposes.
In summary, Microsoft's forthcoming policy change underscores the company's commitment to modernizing its services and ensuring a secure, efficient environment for all users. Organizations should prioritize their migration plans accordingly to align with these updates and maintain seamless operations.
Source: Petri IT Knowledgebase Microsoft to Block Legacy Exchange Public Folder Migrations
