Microsoft is retiring the original Exchange Sync technology many applications still use.

If your business software still depends on EWS-based Exchange Sync, Microsoft's cutoff dates can affect your ability to synchronize with Microsoft 365.

Overview

Exchange Web Services, commonly called EWS, has been used for years by business applications that synchronize Exchange data such as calendars, contacts, tasks, and mailbox-related information.

Microsoft has been moving developers toward Microsoft Graph for several years. In 2023, Microsoft announced that it would begin blocking EWS requests to Exchange Online on October 1, 2026. In 2026, Microsoft described a phased, admin-controllable disablement plan beginning in October 2026 and ending with final EWS shutdown on April 1, 2027.

This change affects Exchange Online / Microsoft 365. Microsoft has stated that EWS retirement for Exchange Online does not apply to on-premises Exchange Server in the same way.

What To Check

  • Do any of your business applications have an Exchange Sync feature?
  • Does the vendor explicitly support Microsoft's newer Graph-based sync technology?
  • Does the application still require an EWS URL or EWS endpoint?
  • Does the application synchronize calendars, contacts, tasks, or mailbox-related data?
  • Can the vendor provide a Graph-compatible version before Microsoft's cutoff dates affect you?

Where ESB Fits

Exchange Sync Bridge is for organizations that still need an EWS-compatible sync endpoint for existing software but need the Microsoft 365 side of the connection to use Microsoft's newer Graph-based technology.

Suggested Source Links

  • Microsoft 365 Developer Blog: Retirement of Exchange Web Services in Exchange Online.
  • Microsoft Exchange Team Blog: Exchange Online EWS, Your Time is Almost Up.
  • Microsoft Exchange Team Blog: Introducing EWSAllowedAppIDs.