http://blogs.technet.com/bpositive/archive/2009/06/19/outlook-2003-support-is-enabled-worldwide.aspxThe June update for services has been finished! This means that you can now use Outlook 2003 with BPOS. There are a couple of considerations relating the oflline address book and free/busy . See the BPOS team blog for details. Also, attachment size hasen-USCommunityServer 2.1 SP1 (Build: 61025.2)