X-Cart forums - Email Message Template

I am having issues with the "Newsletter" module email template (or lack thereof). I have done extensive work with the /common_files/mail/html/html_message_template.tpl file in order to get a nicely laid out html message for my customers. However, the Newsletter module completely ignores this particular body template, and only tacks on the signature template to outgoing "Newsletter" email.

Does anyone here in the forums know how to apply the html_message_template.tpl file to outgoing "Newsletter" emails?