Retain 2.5 or higher
The error indicates that either you have a throttling policy applied or the Exchange server is busy. Microsoft Exchange 2010 uses client throttling policies by default to track bandwidth for each Microsoft Exchange user and enforce bandwidth limits as necessary. Throttling policies should be turned off for the Retain Service Account, because they can affect the performance of Retain for Exchange when accessing mailboxes with a large number of folders and mail items.
1. On a computer that hosts the Microsoft Exchange Management Shell, open the Microsoft Exchange Management Shell.
2. Type these commands:
a. New-ThrottlingPolicy [give it a policy name of your choosing]
b. Set-ThrottlingPolicy [policy name from step "a"] -RCAMaxConcurrency Unlimited -EWSMaxConcurrency Unlimited -EWSMaxSubscriptions Unlimited -CPAMaxConcurrency Unlimited -EwsCutoffBalance Unlimited -EwsMaxBurst Unlimited -EwsRechargeRate Unlimited
c. Set-Mailbox [Retain impersonation user account] -ThrottlingPolicy [policy name from step "a"]
3. To check the policy run the command:
- Get-ThrottlingPolicy -Identity [policy name from step "a"] | Format-List
Which should return something like this: