http://blogs.msdn.com/dgoldman/archive/2005/08/01/446071.aspxOAB Version 4 is a new addition to the Offline Address Book infrastructure. It was designed to help remove most Outlook OAB download related problems Once Exchange 2003 Service Pack 2 has successfully been installed on to the Exchange server, it willen-USCommunityServer 2.1 SP1 (Build: 61025.2)