No, it might be, but that is not my area of experience to be able to help. I use CDO to bypass Outlook because I am sending text files and spreadsheets, but Excel/Outlook can only handle Microsoft file formats. Maybe someone else will chime in with a direct answer to your question...
EDIT:
Outlook advantages:
• have an audit trail in your sent mail
• can directly access Outlook features such as signatures, out box
• doesn't require a reference, therefor is more portable from desktop to desktop
CDO advantages:
• low memory footprint since it is not adding an app to the process
• can send any file type
• quick
• no application issues to deal with