Microsoft has released Update Rollup 6 for Exchange Server 2010 Service Pack 1

Update Rollup 6 for Exchange Server 2010 Service Pack 1 resolves issues that were found in Exchange Server 2010 Service Pack 1 since the software was released. This update rollup is highly recommended for all Exchange Server 2010 Service Pack 1 customers.

For a list of changes that are included in this update rollup, see KB2608646.

  Update Rollup 6 for Exchange Server 2010 Service Pack 1 (KB2608646)