coin/coin/templates/admin/members/member/change_form.html

{% extends "admin/change_form.html" %}
{% load url from future %}
{% block object-tools-items %}
    <li><a href="{% url 'admin:send_welcome_email' id=object_id %}">Envoyer le courriel de bienvenue</a></li>
    {{ block.super }}
{% endblock %}