Exchange Web Services in Exchange Online: phased disablement starts October 1, 2026 and EWS is fully and permanently disabled April 1, 2027, with no…
The dates, and where each one comes from
| Date | What happens | Source |
|---|---|---|
| July 2018 | EWS deprecation announced: no further feature updates | Learn page timeline |
| September 2023 | Disablement date set: “on October 1, 2026, we will start blocking EWS requests from non-Microsoft apps” | Microsoft 365 Developer Blog |
| January 2024 | Midnight Blizzard incident involves EWS; Microsoft says it “elevated the urgency” and widened scope to its own applications | Learn page timeline |
| February 5, 2026 | Phased, admin-controllable plan published; day-level dates confirmed | Exchange Team post; MC1227454 |
| End of August 2026 | Deadline to opt out of the automatic October 1 change (Allow List + EWSEnabled True) — passed
|
Exchange Team post |
| September 2026 | Microsoft pre-populates an AppID Allow List for tenants that never created one, from their own usage | Exchange Team post |
| October 1, 2026 | Tenants still at the default (EWSEnabled Null) are flipped to False as the rollout reaches them; EWS blocked for every app in the tenant |
Exchange Team post; MC1227454 |
| April 1, 2027 | EWS fully and permanently disabled; the EWSEnabled control is removed from tenant admins |
Exchange Team post; MC1227454 |
What's covered
- The dates, and where each one comes from
- How the switch actually works
- On-premises Exchange is not affected — but hybrid is
- What still does not exist in Microsoft Graph
- What to do in the four weeks left
Full guide with every version, risk scores, and live updates: https://endoflife.ai/article-exchange-web-services-retirement-2026
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