Exchange Online: EWS turned off in tenants, re-enabling possible until April 2027

Summary

Microsoft is turning off the Exchange Web Services (EWS) protocol in Exchange Online. In the current first stage, tenant administrators can still re-enable EWS, but this only works until April 2027. Applications that depend on EWS must be updated by then. Confirmed by Microsoft.

What changes?

Applications that use EWS (Apple Mail/Calendar on macOS, classic Outlook on macOS, some Outlook add-ins, outdated Outlook versions on Windows, many backup tools) repeatedly ask for username or password or report that the EWS protocol is not available.

Affected

• Exchange Online tenants in which Microsoft has turned off EWS
• Applications using EWS: Apple Mail/Calendar on macOS, classic Outlook on macOS, Outlook desktop add-ins, outdated Outlook for Windows, third-party backup applications

Preparation and temporary exceptions

Only the tenant administrator can do this; Microsoft support cannot. Temporary until April 2027.

1. In the Message Center, search for "Action may be required: EWS will be disabled in your tenant in 7 days" or "EWS has been disabled in your tenant" to see when EWS was turned off.
2. Option 1: In the Microsoft 365 admin center open Baseline security mode, select "Block access to Exchange Web Services", clear "Block your entire organization from using EWS" and click "Apply change".
3. Then select the same checkbox again and click "Apply change" again. The tenant is then set to EWSEnabled = True with an allow list of apps.
4. Option 2: Connect to Exchange Online PowerShell and check with Get-OrganizationConfig | Fl EWSEnabled. If it shows False, run Set-OrganizationConfig -EWSEnabled $true.
5. The change usually takes under an hour, in rare cases up to 4 hours.
6. To view allowed apps run Get-OrganizationConfig -RetrieveEwsOperationAccessPolicy | Fl EwsAllowedAppIDs. Changes to the allow list take 24 hours.

Check and complete

Long-term: update applications to versions that no longer use EWS, or change self-developed code. Re-enabling EWS stops working in April 2027.

Recommendation

Re-enable EWS now if business applications are affected, then inventory all EWS-dependent apps (backup, add-ins, macOS clients) and ask the vendors for versions without EWS. Plan the migration well before April 2027.

Timeline

1. 21 Oct 2026First stage of EWS disablement is in progress: Microsoft turns EWS off in tenants, and tenant administrators can still re-enable it.

Sources

• Exchange Team Blog: Exchange Online EWS application stopped working? Do this. Vendor · techcommunity.microsoft.com
• Microsoft 365 admin center: Baseline security mode News · admin.cloud.microsoft

Compiled from the sources listed and translated with AI (Claude); status and dates come from the vendor. The vendor’s statements are authoritative. Updated 2 Nov 2026, 01:05.