Log in to Office 365 admin page https://admin.microsoft.com/
Click Show All in the feature pane.
Click Support and follow with New service requests.
In the search field, search for throttling. Select Increase EWS Throttling Policy from the list.
Click Run Tests.
Diagnostic tests are running.
Select the duration in days. The options are 30 days, 60 days, and 90 days. Check the checkbox to acknowledge the change and click Update Settings.
You will get a message showing Success. The update to Exchange Web Services (EWS) throttling policy started. The update will complete within 15 minutes.
Verify that throttling is disabled in Office 365
After 15 minutes, run the test again to check if the changes are applied.
You can see that Exchange Web Services (EWS) is currently not throttled.