In this post, we wanted to share a practical walk-through of discovering which Azure AD app registrations are still using Exchange Web Services (EWS), plus what the Kiosk/Frontline license changes me...
Updated Jun 26, 2026
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Notes From the Field: Finding and Remediating EWS App Usage Before Retirement
Implementing this has been highly problematic.
We had a few apps listed in the EWS usage report, and proceeded to add them to the allow list and enable the EWS Allow list.
Then lots of things started failing.
We have had to add exemptions for Outlook classic teams add ins, Power Automate flows , MTRs and more.
Searching for all the sources each time finds documentation of specific and general issues all over the place, all part of the Microsoft ecosystem and not custom apps.
If you are implementing this - I recommend being well prepared and flexible to add unexpected exemptions to the list.
Why would Power Automate Mail send connector fail? Why has it not been modernised before this date?
MTR is another surprise where okhttp calls failed.
https://learn.microsoft.com/en-us/power-platform/admin/apps-to-allow does not include MTR or the Outlook Classic Teams Addin for example.
StephenBlack you just need to see your EWS usage report and allow EWS Application IDs being used in the report, and I believe you should be good.
Didn't you follow your EWS usage report?
This is the exact reason why I'm leaning towards just setting EWSEnabled to True prior to October and then allowing Microsoft to build my EWS Allow list on my behalf. Like you said, this has been highly problematic with conflicting information all over the place.
Has it been confirmed that Microsoft will only add AppIDs to the EWSAllowedAppIDs list if we change EWSEnabled from Null to "True"? We're currently defaulting to Null but if it needs to be "True" for Microsoft to build our list I'll need to change it. I was hoping they would build the list regardless and at that point we would then decide if we actually needed the Apps they added to the list.
- Nino_Bilic
Microsoft
We will create a list if one does not exist for tenants who are either set to TRUE or NULL, as long as they did not build the list already. Take control of your EWSAllowedAppIDs list before EWS access changes | Microsoft Community Hub.
Thanks for the detailed write-up — this matches exactly what we're running into as we prepare to enable the allow list ourselves.
Would you be able to share the specific App IDs you had to add as exemptions? Especially for:
- Outlook classic Teams add-in
- Power Automate Mail send connector
- MTR devices
- Any of the "and more" you mentioned
Having the exact IDs would save us a lot of the same trial-and-error you went through, and help us go into this better prepared.
thejimmartinWere those first party applications missing in your EWS usage report?
