Changing the connection speed limit


How to change the connection speed limit (Exchange throttling settings).


Exchange Online (Office 365)

As of December 2014, it is not possible to modify throttling policies on your own in Exchange Online. Originally, this was possible via the PowerShell remote connection. However, Microsoft removed throttling-related cmdlets from Exchange Online PowerShell some time ago. If you need to modify your Office 365 throttling settings, contact Microsoft support (Office 365 business support details) to discuss this.

Solution for Exchange Server 2010/2013/2016

When using CodeTwo Exchange Migration, the migration speed depends, among other things, on the target Exchange Web Services (EWS) throttling settings. 

Also, the connection speed of CodeTwo Backup may depend on the settings described below. However, these instructions will most likely be helpful if you've previously configured stricter throttling policies. CodeTwo Backup users should also take a look at our article explaining which factors may influence the backup speed

To make sure your target server's EWS throttling policy is not a bottleneck in your migration/backup, follow the steps below to create a new, unlimited throttling policy and assign it to the account used by the CodeTwo software:

  1. Open the ems Exchange Management Shell (EMS) on the target server.
  2. Execute the following cmdlet to check your current throttling policies:
    Get-ThrottlingPolicy | fl
  3. Create a new throttling policy:
    New-ThrottlingPolicy <ThrottlingPolicyName>
    For example:
    New-ThrottlingPolicy CodeTwoPolicy
  4. Reconfigure the new policy settings in a way that does not limit the migration.
    • Exchange Server 2010:
      Set-ThrottlingPolicy CodeTwoPolicy -RCAMaxConcurrency $null -EWSMaxConcurrency $null -EWSMaxSubscriptions $null -CPAMaxConcurrency $null
    • Exchange Server 2013/2016:
      Set-ThrottlingPolicy CodeTwoPolicy -RCAMaxConcurrency Unlimited -EWSMaxConcurrency Unlimited -EWSMaxSubscriptions Unlimited -CPAMaxConcurrency Unlimited -EwsCutoffBalance Unlimited -EwsMaxBurst Unlimited -EwsRechargeRate Unlimited


      Read more about changing throttling policies in Exchange 2010, 2013 and 2016 on Microsoft's website.

  5. Execute the following cmdlet to assign the newly created policy to the admin account used in CodeTwo software:
    Set-Mailbox "<mailbox name>" -ThrottlingPolicy CodeTwoPolicy
    where <mailbox name> is the name or alias of the mailbox account used by that administrator.

    If the software still reports errors related to the inaccessibility of Exchange, consider assigning the policy to all users in your organization:
    Set-ThrottlingPolicy "CodeTwoPolicy" -ThrottlingPolicyScope Organization


    Changes in throttling policies are applied immediately.

See also:

Microsoft resources: