Microsoft's Exchange Web Services shutdown process now has concrete dates — Here's what you can do to avoid interruption after EWS is permanently disabled

Microsoft's Exchange Web Services (EWS) API has been on its way out since an initial retirement announcement in 2018, but we now have some concrete dates as to when it will officially disappear forever.

Beginning October 1, 2026, Microsoft is rolling out a "phased, admin-controllable disablement plan" that will eventually wrap up with a complete EWS shutdown in Exchange Online on April 1, 2027. Microsoft highlights the fact that these EWS changes only apply to Microsoft 365 and Exchange Online; no changes to EWS are expected in Exchange Server.

That leaves users and admins six months to prepare for the disablement plan, and Microsoft offers some advice to help make the transition as smooth as possible. The plan is to disable EWS one tenant at a time via the EWSEnabled property. A new AppID Allow List is also expected in early 2026, which is essentially an admin whitelist for app access to EWS.

Three values are supported in the EWSEnabled property:

• True: Starting October 2026, only apps in the new Allow List are allowed to access EWS.
• False: Starting October 2026, all EWS is blocked.
• Null: Starting October 2026, all EWS is allowed and the Allow List is ignored.

Microsoft confirms that any tenants with their status still set to Null in the EWSEnabled property on October 1, 2026, will be automatically changed to False, blocking any applications in the tenant.

That's fine if you want to leave EWS blocked, but if not, you should take some proactive measures. Admins who change EWSEnabled to True and create an Allow List before the end of August 2026 will not be included in the automatic rollover to EWSEnabled False on October 1.

Failing to do anything and re-enabling EWS after it's blocked will result in a service interruption. And once April 1, 2027 rolls around, EWS will be permanently disabled, and the EWSEnabled property will be removed.

Microsoft also claims that it might perform scream tests where it turns off EWS temporarily in order to sniff out any missed dependencies before the final shutdown. The company says it will release more info in "the coming weeks."

Why is Microsoft retiring Exchange Web Services (EWS)?

Microsoft's EWS is a cross-platform API that makes it possible for a wide range of apps to access Exchange mailbox data, including messages, calendars, and contacts.

EWS has been around for almost two decades since it got its start in 2007, and it was indeed a useful tool. However, as Microsoft states, "it no longer aligns with today's security, scale, or reliability requirements." In 2023, the company announced it was going forward with its plan to retire EWS, but didn't provide a clear roadmap for the process. That's now changed with this update.

Replacing EWS is Microsoft Graph, a more modern API that provides access to Windows, Microsoft 365, and more. Its feature list is nearly on par "for the vast majority of EWS scenarios," and Microsoft urges users to begin migrating apps to Graph now.

Do you regularly use Microsoft EWS? Are you concerned about the migration process? Have you already made the switch to Graph? Let me know in the comments section!

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