Sendmail form: Fix validation problems

src/pretix/plugins/sendmail/forms.py

@@ -68,7 +68,7 @@ class MailForm(forms.Form):
 
     def clean(self):
         d = super().clean()
-        if d.get('subevent') and d.get('subevents_from'):
+        if d.get('subevent') and (d.get('subevents_from') or d.get('subevents_to')):
             raise ValidationError(pgettext_lazy('subevent', 'Please either select a specific date or a date range, not both.'))
         if bool(d.get('subevents_from')) != bool(d.get('subevents_to')):
             raise ValidationError(pgettext_lazy('subevent', 'If you set a date range, please set both a start and an end.'))

src/pretix/plugins/sendmail/templates/pretixplugins/sendmail/send_form.html

@@ -7,6 +7,7 @@
     {% block inner %}
         <form class="form-horizontal" method="post" action="" enctype="multipart/form-data">
             {% csrf_token %}
+            {% bootstrap_form_errors form %}
             {% bootstrap_field form.recipients layout='horizontal' %}
             {% bootstrap_field form.sendto layout='horizontal' %}
             {% if form.subevent %}