See http://blogs.msdn.com/b/deva/archive/2010/01/19/outlook-2010-why-cdo-1-2-1-not-supported-with-outlook-2010.aspx and http://support.microsoft.com/kb/2028411

>We're running MS Outlook 2007 and on a few machines 2010. The CDO 1.21 patch is able to integrate with the 2007 version but not so with the 2010. Microsoft says that some of the CDO 1.21 has been incorporated into 2010 Outlook but I guess not enough. Is anyone aware of another download like the CDO 1.21 that is available to handle program calls to 2010?