MC1485116: Exchange Online enforces EWSAllowedAppIDs requirement on October 10
Microsoft is ending the EWSEnabled=True fallback within Exchange Online, requiring administrators to whitelist applications by October 10 or face disruptions with third-party tools. This enforcement impacts Microsoft 365 work accounts and Mac email synchronization. Administrators must inventory applications utilizing Exchange Web Services and construct an explicit allow list. While Microsoft plans to auto-populate portions of the list between October 8 and October 9 using traffic from the prior 60 days, teams are advised to build their own lists to prevent blind spots and service interruptions.
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- ✓ Exchange Online will enforce the EWSAllowedAppIDs requirement on October 10.
- ✓ Microsoft is retiring its EWSEnabled=True fallback in Exchange Online.
- ✓ Microsoft plans to fill the allow list on October 8 and October 9 from 60 days of activity.
- ✓ The change threatens to disrupt third-party tools and Mac email synchronization for Microsoft 365 work accounts.
What changed
Microsoft announced the strict enforcement of the EWSAllowedAppIDs requirement taking effect on October 10.
Live updates
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Exchange Online Enforces EWSAllowAppIDs on October 10
Microsoft is ending the EWSEnabled=True fallback within Exchange Online, requiring administrators to whitelist applications by October 10 or face disruptions with third-party tools. This enforcement impacts Microsoft 365 work accounts and Mac email synchronization. Administrators must inventory applications utilizing Exchange Web Services and construct an explicit allow list. While Microsoft plans to auto-populate portions of the list between October 8 and October 9 using traffic from the prior 60 days, teams are advised to build their own lists to prevent blind spots and service interruptions.
Why it matters
Exchange Web Services is entering its final stage before Microsoft removes access, creating potential syncing failures for users relying on Apple Mail and other third-party clients. Apple is actively planning a fix to address the incoming disruption to Mac email. Organizations must manually verify tenant states and register required application IDs to maintain uninterrupted connectivity.
What is confirmed
- Exchange Online will enforce the EWSAllowedAppIDs requirement on October 10.
- Microsoft is retiring its EWSEnabled=True fallback in Exchange Online.
- Microsoft plans to fill the allow list on October 8 and October 9 from 60 days of activity.
- The change threatens to disrupt third-party tools and Mac email synchronization for Microsoft 365 work accounts.
Still unconfirmed
- Apple is planning a fix to counter the Microsoft Exchange shutdown affecting Mac email.
What to watch next
- Execution of the October 8 to October 9 auto-population by Microsoft
- Final enforcement of the EWSAllowedAppIDs requirement on October 10
- Release of any software updates from Apple to address Mac email syncing
confidence 95%Sources used for this update (9)
- Neowin — MC1485116: Exchange Online enforces EWSAllowedAppIDs requirement on October 10
- AppleInsider — Apple plans fix as Microsoft's Exchange shutdown disrupts Mac email
- MacRumors — Microsoft 365 Work Accounts May Stop Syncing in Apple Mail
- Auburn University — Upcoming changes to Microsoft 365 email access
- The Register — Exchange Web Services enters the final stretch before Microsoft pulls access
- www.si.com — Best Betting Sites Canada for October 2026: Expert Tested and Ranked
- 9to5windows.com — Exchange Online Will Enforce the EWSAllowedAppIDs Requirement ...
- www.tun.lat — Exchange Online Enforces the EWS Allow List on October 10 ...
- trustlist.uk — Exchange Online: apps using EWS must be on an allow list from ...
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