Exchange Web Services starts switching off in Exchange Online in October 2026, fully off by April 2027

Exchange Web Services starts switching off in Exchange Online in October 2026, fully off by April 2027

1 October 2026 — The long-announced end of Exchange Web Services (EWS) in Exchange Online has arrived. Microsoft's deprecation page states the timeline plainly: in October 2026, "EWS starts to be disabled globally for all organizations", and in April 2027 it is fully disabled. heise online reported on 30 September 2026 that the staged switch-off begins on 1 October. Microsoft's own page, read on 1 October, gives the month but not the day.

EWS is the old SOAP interface that many third-party mail, calendar, archiving, backup, CRM and room-booking tools use to reach Exchange mailboxes. Microsoft's replacement is Microsoft Graph.

What Microsoft's page says

• The disablement date was set in 2023. After the Midnight Blizzard incident in January 2024, which involved EWS, the scope was widened from third-party applications to all Microsoft applications as well.
• Microsoft offers EWS Usage Reports, an EWS Analyzer tool and a tutorial for AI-assisted code migration to help find and move EWS dependencies.
• A roadmap of remaining Graph gaps lists items still due in the third and fourth quarters of 2026, including full-fidelity import and export for archive, public folder and group mailboxes, In-Place Archive access, an Exchange Admin API, mailbox notes and contact lists. Microsoft says that if a capability is not on that list, you should not plan on a Graph equivalent arriving before EWS is fully disabled.
• Some EWS capabilities will never come to Graph: generic public-folder create, read, update and delete; generic Microsoft 365 Group mailbox item access; and legacy Discovery Mailbox access.

The Mac problem

heise reports that the built-in macOS apps (Mail, Calendar, Reminders, Contacts and Notes) use EWS to sync with Exchange Online, and that Apple has said support for Graph will come in a future update to macOS 27, without a date. heise found no sign of it in macOS 27.0.1. As EWS is switched off, those apps can stop syncing with Microsoft 365 mailboxes. heise says administrators can keep EWS working for listed applications for the coming months through an allow-list; we have not found that detail on Microsoft's page. iPhone and iPad mail use Exchange ActiveSync, not EWS.

What to do

• Run the EWS Usage Reports in the Microsoft 365 admin centre to see which applications still call EWS, and how often.
• Ask each vendor on that list for its Graph migration date in writing. Archiving, backup, e-discovery and migration tools are the most likely to depend on capabilities still on Microsoft's gap list.
• Plan for Mac users: move them to Outlook for Mac, or put the built-in apps on an exception path, until Apple ships Graph support.
• Do not build anything new on EWS. Microsoft is clear that features missing from its roadmap will not arrive before April 2027.
• On-premises Exchange Server is not part of this change; the timeline applies to Exchange Online.

Sources

• Microsoft Learn: Deprecation of Exchange Web Services in Exchange Online — 1 October 2026
• heise online: Komplettausfall droht: Microsoft dreht EWS ab; macOS nicht bereit — 30 September 2026