{% extends "admin/change_form.html" %}
{% load i18n admin_urls %}
{% load url from future %}

{% block object-tools-items %}
<li>
  <span class="span2">
    <a href="{% url 'admin:mail_detail' object_id %}"
       onclick="return showAddAnotherPopup(this);"
       class="big-button add-another">
      <i class="email-item"></i>
      Show</a>
  </span>
{{block.super}}
</li>{% endblock %}