com: fix weekmail for the case of non-existing email addresses

If an email address is set as destination for the Weekmail, the SMTP may
refuse it, and `smtplib` will throw a `SMTPRecipientsRefused` error,
containing the list of refused addresses. This commit provides an
interface for the weekmail sender to quickly unsubscribe the faulty
users, so that the next try sending the weekmail can be performed
successfully.

com/templates/com/weekmail_preview.jinja

@@ -7,15 +7,33 @@
 
 {% block content %}
 <a href="{{ url('com:weekmail') }}">{% trans %}Back{% endtrans %}</a>
-{% if request.GET['send'] %}
-<p>{% trans %}Are you sure you want to send this weekmail?{% endtrans %}</p>
-{% if request.LANGUAGE_CODE != settings.LANGUAGE_CODE[:2] %}
-<p><strong>{% trans %}Warning: you are sending the weekmail in another language than the default one!{% endtrans %}</strong></p>
-{% endif %}
-<form method="post" action="">
-    {% csrf_token %}
-    <button type="submit" name="send" value="validate">{% trans %}Send{% endtrans %}</button>
-</form>
+{% if bad_recipients %}
+    <p>
+    <span class="important">
+        {% trans %}The following recipients were refused by the SMTP:{% endtrans %}
+    </span>
+    <ul>
+    {% for r in bad_recipients.keys() %}
+        <li>{{ r }}</li>
+    {% endfor %}
+    </ul>
+    </p>
+
+    <form method="post" action="">
+        {% csrf_token %}
+        <button type="submit" name="send" value="clean">{% trans %}Clean subscribers{% endtrans %}</button>
+    </form>
+{% else %}
+    {% if request.GET['send'] %}
+        <p>{% trans %}Are you sure you want to send this weekmail?{% endtrans %}</p>
+        {% if request.LANGUAGE_CODE != settings.LANGUAGE_CODE[:2] %}
+            <p><strong>{% trans %}Warning: you are sending the weekmail in another language than the default one!{% endtrans %}</strong></p>
+        {% endif %}
+        <form method="post" action="">
+            {% csrf_token %}
+            <button type="submit" name="send" value="validate">{% trans %}Send{% endtrans %}</button>
+        </form>
+    {% endif %}
 {% endif %}
 <hr>
 {{ weekmail_rendered|safe }}

com/views.py

@@ -39,6 +39,7 @@ from django.core.exceptions import PermissionDenied
 from django import forms
 
 from datetime import timedelta
+from smtplib import SMTPRecipientsRefused
 
 from com.models import Sith, News, NewsDate, Weekmail, WeekmailArticle, Screen, Poster
 from core.views import (
@@ -414,22 +415,35 @@ class NewsDetailView(CanViewMixin, DetailView):
 # Weekmail
 
 
-class WeekmailPreviewView(ComTabsMixin, CanEditPropMixin, DetailView):
+class WeekmailPreviewView(ComTabsMixin, QuickNotifMixin, CanEditPropMixin, DetailView):
     model = Weekmail
     template_name = "com/weekmail_preview.jinja"
     success_url = reverse_lazy("com:weekmail")
     current_tab = "weekmail"
 
+    def dispatch(self, request, *args, **kwargs):
+        self.bad_recipients = []
+        return super(WeekmailPreviewView, self).dispatch(request, *args, **kwargs)
+
     def post(self, request, *args, **kwargs):
         self.object = self.get_object()
-        try:
-            if request.POST["send"] == "validate":
+        if request.POST["send"] == "validate":
+            try:
                 self.object.send()
                 return HttpResponseRedirect(
                     reverse("com:weekmail") + "?qn_weekmail_send_success"
                 )
-        except:
-            pass
+            except SMTPRecipientsRefused as e:
+                self.bad_recipients = e.recipients
+        elif request.POST["send"] == "clean":
+            try:
+                self.object.send()  # This should fail
+            except SMTPRecipientsRefused as e:
+                users = User.objects.filter(email__in=e.recipients.keys())
+                for u in users:
+                    u.preferences.receive_weekmail = False
+                    u.preferences.save()
+                self.quick_notif_list += ["qn_success"]
         return super(WeekmailPreviewView, self).get(request, *args, **kwargs)
 
     def get_object(self, queryset=None):
@@ -439,6 +453,7 @@ class WeekmailPreviewView(ComTabsMixin, CanEditPropMixin, DetailView):
         """Add rendered weekmail"""
         kwargs = super(WeekmailPreviewView, self).get_context_data(**kwargs)
         kwargs["weekmail_rendered"] = self.object.render_html()
+        kwargs["bad_recipients"] = self.bad_recipients
         return kwargs