Exchange Server MAPI client and Collaboration Data Objects 1.2.1 is a system requirement when installing Symantec Mail Security for Microsoft Exchange (SMSMSE) on an Exchange 2007 or Exchange 2010 server with the Mailbox role. When you attempt to install MapiCdo the error "Messaging API and Collaboration Data Objects 1.2.1 cannot be installed with Microsoft Outlook" occurs.
Beginning with Exchange 2007, Microsoft no longer provides the Messaging API (MAPI) client libraries or Collaboration Data Objects (CDO) 1.2.1 as part of the product installation.
You must remove Outlook before Installing MapiCdo.