Edit full html in email templates

Is there a way to edit the full html of the email templates.

For example if I want to set a different doctype, or want to add tags in the head, or some

Allright, I have found a solution for editing the HEAD. This is possible by creating a script and setting the selector to ‘head’. This way I can append and prepend all the things I need before the html is being rendered.

I have yet to found a solution to edit the doctype, if anyone as a solution I would like to know.

Kind Regards,
Sven Slijkoord