mattermost/server/templates/messages_notification.mjml

<mjml>
  <mj-head>
    <mj-include path="./partials/style.mjml" />
    <mj-include path="partials/message_attachment_styles.mjml" />
  </mj-head>
  <mj-body css-class="emailBody">
    <mj-wrapper mj-class="email">
      <mj-include path="./partials/logo.mjml" />
      <mj-include path="./partials/header.mjml" />
      <mj-raw>{{range .Props.Posts}}<div class="postCard"></mj-raw>
        <mj-section css-class="messageCard" padding="0px">
          <mj-group>
            <mj-include path="./partials/message_avatar_col.mjml" />
            <mj-include path="./partials/sender_info_col.mjml" />
            <mj-include path="partials/message_attachment.html" type="html" />
            <mj-include path="./partials/message_button.mjml" />
          </mj-group>
        </mj-section>
      <mj-raw></div>{{end}}</mj-raw>
      <mj-section padding="16px 0px 40px 0px">
        <mj-column>
          <mj-text css-class="footerTitle" padding="0px">
            {{.Props.NotificationFooterTitle}}
          </mj-text>
          <mj-text css-class="footerInfo" padding="0px">
            <a href="{{.Props.SiteURL}}">{{.Props.NotificationFooterInfoLogin}}</a>{{.Props.NotificationFooterInfo}}
          </mj-text>
        </mj-column>
      </mj-section>
      <mj-include path="./partials/email_footer.mjml" />
    </mj-wrapper>
  </mj-body>
</mjml>