Exchange Web Services (EWS) throttling in Exchange Online
Throttling can slow your Office 365 migration by affecting your ability to send and receive data from the Office 365 servers through Exchange Web Services (EWS). The throttling process was designed to protect servers by placing limits on how much information can be transferred in a specific period. For your EWS migration, throttling will cause it to be much slower, and if not carefully managed, may result in frequent disconnection and error messages.
How to prevent EWS throttling in Office 365
It’s impossible to fully avoid Exchange Web Services throttling, as throttling occurs in Microsoft’s hands, but there are a few precautions that can be taken:
- Maintain sufficient intervals between multiple migration batches.
- Avoid running heavy concurrent tasks during the migration process.
- Throttling requests to the same mailbox during Office 365 operations.
- Reduce unnecessary mail processing activities in the mailbox during migration./li>
Steps to increase EWS throttling policy limits in Microsoft 365
Manual management of throttling policies in Exchange Online has been discontinued. Previously, these policies were able to be changed with remote PowerShell, but Microsoft has taken away that ability. Though it is possible to ask Microsoft to briefly increase the EWS throttling for you through the Microsoft 365 admin center or with the support of Microsoft support for assistance.
- Sign in to your Microsoft 365 Admin Center account
- Click ‘…Show all’ on the left side menu.
- Navigate to ‘Support’ > ‘Help & support’
- Type ‘Increase EWS Throttling Policy’ in the search bar, press the Enter key, then click the ‘Run Tests’ button
- Wait till the diagnostic test completes. Next, choose either 30, 60, or 90 days to disable the EWS Throttling Policy. Ensure to check the acknowledgement checkbox and then click the ‘Update’ button
- Exchange Web Services (EWS) throttling policy updates have been started. It will be completed within 15 minutes.
- After 15 minutes, perform the test (Step 4) to confirm that the throttling has been disabled.
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