<mjml>
  <mj-body>
    <mj-include path="./_header.mjml" />

    <mj-section>
      <mj-column>
        <mj-text>foo</mj-text>
      </mj-column>
    </mj-section>

    <mj-include path="./_footer.mjml" />
  </mj-body>
</mjml>
