When you copy messages to a Discovery mailbox by selecting the Copy Search Results option in eDiscovery in a Microsoft Exchange Server 2013 environment, you receive an error message that resembles the following:
Failed exporting item id: from source id: SourceID with error: [NumberOfItemsMismatched] Export failed with error type: 'NumberOfItemsMismatched'. Message: Expected number of items (Number) supposed to write to the list is not matched with actual (Number)
To resolve this issue, install the following cumulative update:
2892464 Description of Cumulative Update 3 for Exchange Server 2013
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about the Copy Search Results option in eDiscovery, go to the following Microsoft website: