mailcow-dockerized/data/web/templates/mailbox/tab-mailbox-defaults.twig

<div role="tabpanel" class="tab-pane fade" id="tab-mailbox-defaults" role="tabpanel" aria-labelledby="tab-mailbox-defaults">
  <div class="card mb-4">
    <div class="card-header d-flex">
      <button class="btn d-md-none flex-grow-1 text-start" data-bs-target="#collapse-tab-mailbox-defaults" data-bs-toggle="collapse" aria-controls="collapse-tab-mailbox-defaults">
        {{ lang.mailbox.mailbox_defaults }} <span class="badge bg-info table-lines"></span>
      </button>
      <span class="d-none d-md-block">{{ lang.mailbox.mailbox_defaults }} <span class="badge bg-info table-lines"></span></span>
    </div>
    <div id="collapse-tab-mailbox-defaults" class="card-body collapse text-muted" data-bs-parent="#mail-content">
      {{ lang.mailbox.mailbox_defaults_info }}
    </div>
  </div>
</div>