Exchange Throttling Policy

If you need a higher execution speed of the EWS for migration purposes, then you could create a new throttling policy in the following way, which you can assign to the mailboxes you want to process.

Exchange 2010

New-ThrottlingPolicy ExMixedFoldersPolicy

Set-ThrottlingPolicy ExMixedFoldersPolicy -EWSMaxConcurrency $null

Set-Mailbox [MAILBOXNAME] -ThrottlingPolicy ExMixedFoldersPolicy

Exchange 2013 and up

New-ThrottlingPolicy ExMixedFoldersPolicy

Set-ThrottlingPolicy ExMixedFoldersPolicy -EwsCutoffBalance Unlimited -EwsMaxBurst Unlimited -EwsRechargeRate Unlimited -EWSMaxConcurrency unlimited

Set-Mailbox [MAILBOXNAME] -ThrottlingPolicy ExMixedFoldersPolicy

Office 365

With Office 365, it is not possible to change the throttling policy like you want to have it, but there is a possibility to increase it temporarily for some days. To do this, proceed as follows:

• Login to the Microsoft 365 Admin Center => Support => new service request
• Now enter the words "increase EWS throttling policy" into the "Need help" dialog.
• Click the "Run Tests" button
• After that you get the option to tell an amount of days while you want to have the increased value