SBS 2008 runs Microsoft Exchange Server 2007. On December 11, 2012 Microsoft released Update Rollup 9 (UR9/KB 2746157) for the Exchange Server 2007 running Service Pack 3. It’s important to keep your Exchange server up-to-date with service packs and update rollups.
Before installing this (or any) update, it is strongly suggested that you make sure that you have a recent full backup of your SBS server, and that you plan to reboot your server BEFORE installing this update, as well as AFTER installing it. You want to ensure that you have a properly running server before installing updates.
UR9 can take up to 15 minutes to install. But as there are no intermediate prompts, go ahead and kick it off, and then do something else other than stare at the progress bar!
After installing the update successfully, reboot your server, open up Services (services.msc) and verify that all Exchange services that are set to start automatically are indeed running.