Impact of Exchange throttling policy on EdbMails application

What is throttling?

Throttling is a reactive response against over utilization of system resources that may affect service reliability and functionality. It imposes a limit on the number of concurrent call requests that can be executed at the same time.

Impact Exchange throttling policy on EdbMails application:

Exchange throttling policy affects the backup and migration speed. It gives number of errors during the operation. Throttling is one of the reasons for the errors related to insufficient impersonation rights that may appear frequently.

How to avoid throttling issue?

Create a custom throttling policy with limits higher than the default ones or even disable these limits and assign it to the user account used in the EdbMails application during migration.

Steps to create a custom throttling policy

Note: It will not possible to change throttling policies on your Exchange Online. However, it is possible to increase the throttling policy temporarily.

• Open Exchange Management Shell (EMS).
• Run the following cmdlet to check current throttling
  
  

  Get-ThrottlingPolicy | fl

• Create a new throttling policy
  
  

  New-ThrottlingPolicy <Throttling_Policy_Name>

  For example:

  New-ThrottlingPolicy EdbMailsPolicy

• New policy settings have to be reconfigured in a way that does not hinder the backup or migration tasks. Use $null or Unlimited values to use custom values or to disable the limitation.
  • For Exchange Server 2010 version:
    
    

    Set-ThrottlingPolicyEdbMailsPolicy -RCAMaxConcurrency $null -EWSMaxConcurrency $null-EWSMaxSubscriptions $null -CPAMaxConcurrency $null

  • For Exchange Server 2013 and later versions:
    
    

    Set-ThrottlingPolicyEdbMailsPolicy -RCAMaxConcurrency Unlimited -EWSMaxConcurrency Unlimited-EWSMaxSubscriptions Unlimited -CPAMaxConcurrency Unlimited -EwsCutoffBalanceUnlimited -EwsMaxBurst Unlimited -EwsRechargeRate Unlimited

    For more details for changing throttling policies in Exchange 2010, 2013,2016 and 2019, refer Microsoft's website.

• After creating a throttling policy,it has to be assigned to particular accounts, otherwise the new throttling policy is of no use.
• Run the following cmdlet to assign the newly created policy (e.g. EdbMailsPolicy) to the admin account of EdbMails application:
  
  

  Set-Mailbox "<mailbox name>" -ThrottlingPolicy EdbMailsPolicy

  Where <mailbox name> is the name or alias of the mailbox account.

  Use the below cmdlet to assign the throttling policy to all users in an organization:

  Set-ThrottlingPolicy "EdbMailsPolicy" -ThrottlingPolicyScope Organization