Drag and drop editors are powerful tool as they make HTML design available to people without having to actually code HTML. The tradeoff is they are restrictive. There will always be some HTML design possible that no drag and drop editor can handle.
To meet the needs of advanced users we provide a pure HTML editor. You access this at the bottom of the template chooser in the drag and drop editor.
This takes you to a straight code editor. The editor does syntax highlighting but really it's just a big dumb text editor that doesn't understand the code.
You can add contact merge fields in your code. The available merge field tags are listed on the left for reference.
The preview step renders the email.