The IMsgServiceAdmin::RenameMsgService method assigns a new name to a message service. This method is not currently supported.
See IMsgServiceAdmin : IUnknown.
HRESULT RenameMsgService(
  LPMAPIUID lpUID,        
  ULONG ulFlags,          
  LPTSTR lpszDisplayName  
);
 Clients wanting to assign a new name to a message service should assign a new name to its PR_SERVICE_NAME property. The names of service providers in a message service are stored in their PR_DISPLAY_NAME properties.