This article provides a solution for addressing Microsoft Exchange Web Services (EWS) throttling, which can impact mailbox migrations in Microsoft 365.
Issue: EWS Throttling Impacting Migrations
Microsoft imposes rate limits on Exchange Web Services (EWS) to maintain service stability. When these limits are reached, they can throttle ongoing migrations of Microsoft mailboxes, leading to slower migration speeds or failures.
- Impacted Services: This solution specifically addresses throttling for Microsoft mailboxes using EWS.
- Services Not Covered: This solution will not resolve throttling issues on OneDrive, Personal Sites, or SharePoint Sites.
Solution: Temporarily Increasing EWS Throttling Limits
Microsoft offers a diagnostic tool within the Microsoft 365 Admin Center to temporarily increase EWS throttling policy limits.
Steps to Increase EWS Throttling Limits:
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Sign in to Microsoft 365 Admin Center:
- Go to the Microsoft 365 Admin Center.
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Access Help and Search:
- Click on the Help icon (usually a question mark or speech bubble) located in the top corner of the screen.
- In the search bar, type
Increase EWS Throttling Policy.
- Select the suggested article that appears in the search results.
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Run Diagnostics:
- In the 'Run diagnostics' section displayed, select Run Tests.
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Evaluate Diagnostic Results:
- If the diagnostic returns a message stating "The Exchange Web Services are throttled", you will have the option to adjust the throttling policy.
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Adjust Policy Duration:
- From the 'Duration (Days)' dropdown menu, choose the period you wish to relax the policy for (options typically include 20, 60, or 90 days).
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Acknowledge Changes:
- Place a tick in the checkbox to acknowledge that you understand and agree to make the specified changes.
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Apply Settings:
- Select Update Settings to apply the changes to your EWS throttling policy.
Important Considerations
- Activation Time: Changes can take up to 30 minutes to take effect.
- Microsoft-Controlled Process: This is purely a Microsoft process and diagnostic tool, not a CloudM feature.
- Subject to Change: Microsoft may change or remove this diagnostic and its functionality in the future without prior notice to CloudM.