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Acronis Cyber Protect Cloud: Temporarily Disable EWS Throttling in Microsoft 365

How to reduce Exchange Web Services (EWS) throttling issues during Microsoft 365 backups

Link to article

https://care.acronis.com/s/article/71130-Acronis-Cyber-Protect-Cloud-How-to-temporarily-disable-EWS-throttling-in-Office-365?language=en_US

Overview

Microsoft 365 backups that rely on Exchange Web Services (EWS) may experience performance issues or failures due to EWS throttling imposed by Microsoft. In certain scenarios, throttling can limit the speed or reliability of mailbox backups performed by Acronis Cyber Protect Cloud.

This article explains how EWS throttling can be temporarily disabled to help complete backups or troubleshooting activities.

Applies to

  • Acronis Cyber Protect Cloud

  • Microsoft 365 mailbox protection using Exchange Web Services (EWS)

What Is EWS Throttling

EWS throttling is a Microsoft-enforced mechanism designed to protect Exchange Online from excessive API usage. When throttling is applied:

  • Backup operations may slow down significantly

  • Mailbox backups may fail or stall

  • Backup jobs may take longer than expected to complete

When to Disable EWS Throttling

Temporarily disabling EWS throttling may be useful:

  • During initial Microsoft 365 onboarding with large mailbox counts

  • When troubleshooting persistent backup failures related to EWS limits

  • For short-term remediation of performance issues

Important: This change should only be applied temporarily and reverted once the required operation is complete.

How to Disable EWS Throttling

EWS throttling is disabled by applying a custom throttling policy in Microsoft 365 and assigning it to the affected user accounts.

High-level steps:

  1. Connect to Exchange Online PowerShell using an account with sufficient permissions.

  2. Create or modify a throttling policy that disables EWS limits.

  3. Assign the throttling policy to the required Microsoft 365 user accounts.

  4. Allow time for the policy to take effect.

  5. Run or re-run the Acronis backup jobs.

Exact PowerShell commands are provided in the vendor article and should be followed carefully.

Impact

  • Disabling throttling can significantly improve backup speed and reliability.

  • Removing throttling limits may increase API usage against Microsoft 365.

  • Leaving throttling disabled permanently is not recommended and may breach Microsoft service best practices.

Action Required

  • Apply EWS throttling changes only for affected users and only temporarily.

  • Monitor backup performance after the change.

  • Revert the throttling policy once backups complete successfully.

  • Consider staggering backup schedules or optimising tenant configuration to avoid future throttling issues.

Additional Information

  • EWS throttling behaviour is controlled entirely by Microsoft and may change over time.

  • Microsoft Graph-based backups may be less affected by EWS throttling in newer environments.

  • Always review Microsoft and Acronis guidance before applying throttling changes in production tenants.