To prevent possible issues in an Exchange 2010 Service Pack 1 or later organization, you should create custom throttling policies, apply them to the Exchange Accounts and then restart the Microsoft Exchange Throttling Service.
To do this, run the following PowerShell commands for each Exchange Account:
Set-ThrottlingPolicy <QMM_Exchange_Account_Throttling_Policy_Name> -PowerShellMaxConcurrency <MaxConcurrency>
Set-ThrottlingPolicy <QMM_Exchange_Account_Throttling_Policy_Name> –EWSMaxConcurrency $null –EWSPercentTimeInAD $null –EWSPercentTimeinCAS $null –EWSPercentTimeInMailboxRPC $null –EWSMaxSubscriptions $null –EWSFastSearchTimeoutInSeconds $null –EWSFindCountLimit $null
Set-ThrottlingPolicyAssociation -Identity <QMM_Exchange_Account_Name> -ThrottlingPolicy <QMM_Exchange_Account_Throttling_Policy_Name>
Restart-Service -Name MSExchangeThrottling
where MaxConcurrency is the number of Migration Agent for Exchange (MAgE) instances simultaneously working with Exchange 2010 server, multiplied by the value of 5.
NOTE: To ensure stable operation of MAgE agents when working with Microsoft Exchange 2010, you should increase the number of permitted user connections. For that, change the value for the MaxSessionsPerUser parameter using the client throttling policies, as follows: