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Notes from the field: testing EWSAllowedAppIDs safely

The_Exchange_Team's avatar
The_Exchange_Team
Platinum Contributor
Aug 20, 2026
As customers prepare for the final phase of Exchange Web Services (EWS) retirement in Exchange Online, many are asking the same practical question: how can I prove that EWSAllowedAppIDs is working be...
Updated Oct 14, 2026
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Pankaj9873's avatar
Pankaj9873
Brass Contributor
Aug 20, 2026

Ok, Thasnk for the details explanation. if I understood the order, please correct me if I am wrong.

we already have EWSEnabled set null.

  1. We first need to AllowAPPIDs, then wait for 24 hours to get it replicated,?
  2. then, after 24 hours enabled EWSEnabled =True?
  3. or we can do both steps at same time?
  4. and, if it does not work as expected and we set EWSEnabled=Null so do we need to remove AppID we added or its not required. 
  5. Microsoft will ignore means, we do not need to set EWSEnabled =True again?
  • Nino_Bilic's avatar
    Nino_Bilic
    Icon for Microsoft rankMicrosoft
    Aug 20, 2026

    No, you should not change AppID allow list and EWSEnabled at the same time. Again, I suggested exact steps with a reason; you want your results to be predictable and control exactly when settings will take place. Allow 24 hours for AppID allow list setting to sit. Then choose the time when you want to flip EWSEnabled to True and know that you will see results in max 1 hour. If you changed both concurrently then you are not quite sure when both things will take effect and you might find yourself in a situation you did not expect.

    If things are not working, you need to figure out what was wrong and fix it and test again (if you need to put any apps on the allow list). And yes, before October comes around your EWSEnables should be set to True, if you need EWS to keep working, as starting October, we will start to flip any EWSEnabled from Null to False. So unless your EWS Enabled is set to True, we might disable your EWS then.

    (I'll make a few tweaks in my original reply above to clarify)

    • Pankaj9873's avatar
      Pankaj9873
      Brass Contributor
      Aug 26, 2026

      Nino_Bilic​ While we first populate the AppID and set the EWSEnabled = True after 24 hours, I hope there will be no impact to the application during the replication or after the replication until I set the EWSEnabled to True?

      I understand when everything set if it does not work then I need to troubleshoot while checking Entra sign-in logs. or If there is any other steps for troubleshooting. 

      Just wanted to know\check that application will only impact or would not work when EWSEnabled set to True along with AppIDs and not during replication.