While Public Folders will remain accessible to users through Outlook, Microsoft is deprecating EWS access for third‑party applications in October 2026. As a result, applications like CiraSync Cloud will no longer be able to read or sync data that resides directly in Public Folders.
To ensure uninterrupted contact and calendar synchronization, Public Folder–based sync tunnels must be migrated to a new, supported source.
What Is Changing — and Why It Matters
Public Folder Access Is Changing for Third‑Party Apps
- Users will continue to see and access Public Folders in Outlook.
- However, starting October 2026, third‑party applications will lose access to Public Folders in Exchange Online due to Microsoft EWS deprecation.
- This means CiraSync Cloud will no longer be able to sync contact or calendar data directly from Public Folders.
Without action, sync tunnels that rely on Public Folders will eventually stop functioning.
The Recommended Solution
To continue syncing data that currently lives in Public Folders in Exchange Online, the data must be migrated to a supported mailbox source.
We recommend migrating your Public Folder data to:
- ✅ A Shared Mailbox (most common)
- ✅ A User Mailbox (if preferred for your configuration)
Both options are fully supported by Microsoft Graph and ensure long‑term compatibility.
Automatic Migration, No Manual Cleanup Required
To make this transition as smooth as possible, CiraSync has designed a backend migration tool that:
- ✅ Automatically migrates contact and calendar data from the Public Folder into the new mailbox source
- ✅ Updates your existing sync tunnel configuration to use the new source
- ✅ Preserves data consistency
- ✅ Prevents duplication
- ✅ Requires no manual export, re‑import, or reconfiguration by you
The migration runs safely in the background. Migration time may vary depending on the amount of data being transferred.
What Customers Need to Do
Because this change involves backend changes to your sync tunnels, it must be completed by CiraSync Support.
To get started, please contact Support and provide:
- The Shared Mailbox or User Mailbox you want to use as the new source
- The folder name where the migrated contacts or calendars should live
Our team will take care of the rest.
Outcome After Migration
Once migration is complete:
- Your data will live in a Graph‑supported mailbox
- Your sync tunnels will continue running without interruption
- Your environment will be fully prepared for EWS deprecation
- No data duplication or loss will occur
Need Assistance?
Talk to a human at CiraSync Support to schedule your migration, or discuss the best mailbox option for your environment. We strongly recommend completing this transition well ahead of October 2026 to avoid any disruption.
