Any change getting an html block to Drag and Drop HTML editor soon (or alternatively HTML source view to the current Drag and Drop blocks)? Drag and drop allows global styles which is great and yes, you can mess things up (break CSS inheritence) with your own HTML, but currently it is just way too limiting to try to survive without the possibility to tweak the html when needed. Could you consider adding the HTML block (or HTML source code view) perhaps with a warning that "use this at your own risk, you will most likely mess things up".
Obviously there are other editor types that allow editing the html, but there is a need to have a highly detailed html header and footer in an email (custom html) and then have the body with stable styling (the part that is most often edited by users who do not know html). Currently Drag and Drop does not allow this. Nor does block editor.