Make it optional to notify user on order change

src/pretix/control/forms/orders.py

@@ -90,6 +90,14 @@ class OtherOperationsForm(forms.Form):
             'Use with care and only if you need to. Note that rounding differences might occur in this procedure.'
         )
     )
+    notify = forms.BooleanField(
+        label=_('Notify user'),
+        required=False,
+        initial=True,
+        help_text=_(
+            'Send an email to the customer notifying that their order has been changed.'
+        )
+    )
 
     def __init__(self, *args, **kwargs):
         kwargs.pop('order')

src/pretix/control/templates/pretixcontrol/order/change.html

@@ -175,6 +175,7 @@
                         </div>
                     {% endif %}
                     {% bootstrap_field other_form.recalculate_taxes layout="control" %}
+                    {% bootstrap_field other_form.notify layout="control" %}
                 </div>
             </div>
         </div>

src/pretix/control/views/orders.py

@@ -600,7 +600,12 @@ class OrderChange(OrderView):
         return True
 
     def post(self, *args, **kwargs):
-        ocm = OrderChangeManager(self.order, self.request.user)
+        notify = self.other_form.cleaned_data['notify'] if self.other_form.is_valid() else True
+        ocm = OrderChangeManager(
+            self.order,
+            user=self.request.user,
+            notify=notify
+        )
         form_valid = self._process_add(ocm) and self._process_change(ocm) and self._process_other(ocm)
 
         if not form_valid:
@@ -611,7 +616,10 @@ class OrderChange(OrderView):
             except OrderError as e:
                 messages.error(self.request, str(e))
             else:
-                messages.success(self.request, _('The order has been changed and the user has been notified.'))
+                if notify:
+                    messages.success(self.request, _('The order has been changed and the user has been notified.'))
+                else:
+                    messages.success(self.request, _('The order has been changed.'))
                 return self._redirect_back()
 
         return self.get(*args, **kwargs)