MailChimp doesn't have a simple enough html template out of the box.
Here's the steps to create a simple HTML template.
- In MailChimp, go to the Templates page, click the "Create Template" button.
- Select the "Code Your Own" starting point, and "Paste in code".
- The HTML editor will open. On the right side, select all the HTML and delete it.
- Paste in the contents of simple.html.
- Click "Save and Exit". Give the template a name when prompted.