Exchange Server 2010 SP3 Update Rollup 8, update has been recalled and is no longer available on the download center pending a new RU8 release.
Because of an issue has been identified in this update – issue impacts the ability of Outlook to connect to Exchange, and Exchange Team taking the action to recall the RU8 to resolve this problem. It will be delivered and revised RU8 package as soon as the issue can be isolated, corrected, and validated,
Customers should not proceed with deployments of this update until the new RU8 version is made available. Customers who have already started deployment of RU8 should rollback this update.