Microsoft has released the Update Rollup 2 for Exchange Server 2010. This update resolves issues that were found in Exchange Server 2010 since the software was released. This rollup is highly recommended for all Exchange Server 2010 customers.
This is a cumulative update and replaces rollup 1. Any interim Updates (custom fixes from Microsoft Support, in response to a support call) for Exchange Server 2010 must be uninstalled prior to installing this update rollup. Microsoft Update cannot detect update rollups on Exchange Server 2010 mailbox servers that are part of a database availability group (DAG).