How to change on Email Headers like (Content-Transfer-Encoding) in Siebel email treatment?

Hi All,

Like what we can configure and achieve in siebel outbound communication manager for changing the email header information like (Content-Transfer-Encoding) when we change the parameter in Communication and Driver profile parameter (text/plain encoding, or text/html encoding), the email will be sent by using the configured encoding, but as siebel email marketing is not using the Outbound communication manager, how can we configure like this configuration while sending an email treatments to take the preferred encoding needed.

here is attached Sample Email Generated by Siebel Marketing Campaign, the Content Transfer Type is auto selected by siebel