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Updated Oct 27, 2026
Version 21.0
Blog Post
Hi Greg,
Regarding Public Folders, the Exchange Team stated in its November 2024 announcement: "After evaluating the usage of Public Folders, we have decided to restrict programmatic access to Public Folders to supported Outlook clients only, and for bulk Import/Export purposes."
Would you please clarify whether this restriction also applies to third-party applications that access Public Folders using MAPI.
For context, we have an application that accesses Exchange Online Public Folders using the MAPI provider installed with Microsoft 365 Apps for Enterprise. It uses an existing Outlook Classic MAPI profile for authentication and connectivity, with communication to Exchange Online taking place using only MAPI over HTTP.
Are there any plans to restrict or block MAPI over HTTP requests originating from third-party applications that use Outlook's MAPI provider?
Will this type of access continue to be permitted for as long as Outlook Classic remains a supported client?
We want to move away from Public Folders, but would like to understand whether this represents an immediate risk to existing applications or whether it is something we can plan to address alongside the eventual retirement of Outlook Classic.
Thanks.