Are you using software that communicates with Exchange Online? Then there's a good chance that this software uses Exchange Web Services (EWS). Microsoft is disabling EWS in Exchange Online. This is happening now, tenant by tenant.

What is the plan?

  • Since October 1, 2026, Microsoft will gradually disable EWS. EWS will be blocked unless you set up an allowlist with app IDs and explicitly enable EWS.
  • On April 1, 2027, EWS will be permanently removed from Exchange Online for everyone. An allowlist will no longer help.

Exchange Server on-premises will not change. This only affects Exchange Online.

Which software does this affect?

EWS has long been the standard for connections with Exchange. Think of:

  • CRM and ERP systems that synchronize emails or calendars;
  • backup and archiving solutions;
  • tools for booking rooms or sharing calendars;
  • older mail clients and mobile apps;
  • custom scripts and connections.

What should you do?

  1. Identify which apps use EWS. Use the reports in the Microsoft 365 admin center and the sign-in logs in Entra.
  2. Ask your vendors about their plan. Modern software uses Microsoft Graph. Ask when their Graph version will be available.
  3. Temporarily set up an allowlist for apps that are not yet ready. They will continue to work until April 1, 2027, at the latest.
  4. Convert custom connections to Microsoft Graph. Start this now, as it often takes more time than you think.
  5. Check your licenses. Microsoft mentions Exchange Online Kiosk, Microsoft 365 F1, and F3 among the licenses that require extra attention.

What happens if you do nothing?

Connections suddenly stop. Calendars no longer synchronize, backups fail, or email no longer reaches your CRM. You often notice this only when users complain.

More changes ahead

EWS is not the only change. Teams Live Events will stop: events scheduled before June 30, 2026, can continue until February 28, 2027. After that, use Teams town halls. And for Windows 10, you are now paying for the second year of ESU. Read more in Windows 10 ESU year 2.

Do you want to ensure that your connections continue to work? 365 Angels can inventory your EWS usage and assist with the transition to Microsoft Graph. Contact us.