Consider the following scenario:
You perform a discovery search in mailboxes in a Microsoft Exchange Server 2010 environment.
You use multiple keywords to perform a search.
The number of the search results exceed 1000.
In this scenario, the server only reports 1000 search results.
This issue occurs because the maximum size that the content indexing engine can return is 1000, and the size is smaller than the call buffer size of 4096. Therefore, when multiple calls are sent to the content indexing engine for estimating, the store stops processing the calls when the size exceeds 1000.
To resolve this issue, install the following update rollup:
2645995 Description of Update Rollup 1 for Exchange Server 2010 Service Pack 2
For more information about multi-mailbox search, visit the following Microsoft website: