Exchange Web Services (EWS) is a web service that enables you to access Exchange Online data. By default, Exchange Online uses throttling to protect the performance and availability of the service for all users. The throttling can be disabled via Office 365.
Disable via Office 365
1. Sign into Office 365 Admin page
2. Click on Customize navigation in the feature pane.
3. Check the Select All and click Save.
4. Click the Need Help, or click Support and follow with New service requests
5. In the search field, search for EWS Throttling. Select Increase EWS Throttling Policy from the list and press Enter.
6. Click on Run Tests.
7. Allow the diagnostics test to complete.
8. Once completed, select the option of 30, 60 or 90 days for which the EWS Throttling Policy will be disabled. Ensure the acknowledgement checkbox is checked. Click on Update Settings.
9. EWS throttling will now be removed for the duration you specified.
10. The update to Exchange Web Services (EWS) throttling policy has been initiated. The update will complete within 15 minutes.
11. Run the test (Step 6) after 15 minutes to verify that the throttling had been disabled.