MTK 2.1.x or higher
Exchange 2013 and 2016
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.
MAKE A NOTE OF YOUR CURRENT POLICY AND IT IS RECOMMENDED AFTER YOUR MIGRATION THAT YOU SET IT BACK.
1. On a computer that hosts the Microsoft Exchange Management Shell, open the Microsoft Exchange Management Shell.
2. Type these commands:
a. Set-ThrottlingPolicy GwavaUnlimited -ThrottlingPolicyScope Organization
Setting the throttling policy must be set at the organization level so that it affects every mailbox the impersonation account enters.
- Get-ThrottlingPolicy -Identity [policy name] | Format-List
Which should return something like this: