Model-based mail queuing

src/pretix/base/shredder.py

@@ -51,7 +51,7 @@ from pretix.api.serializers.waitinglist import WaitingListSerializer
 from pretix.base.i18n import LazyLocaleException
 from pretix.base.models import (
     CachedCombinedTicket, CachedTicket, Event, InvoiceAddress, OrderPayment,
-    OrderPosition, OrderRefund, QuestionAnswer,
+    OrderPosition, OrderRefund, OutgoingMail, QuestionAnswer,
 )
 from pretix.base.services.invoices import invoice_pdf_task
 from pretix.base.signals import register_data_shredders
@@ -329,6 +329,10 @@ class EmailAddressShredder(BaseDataShredder):
             sleep_time=2,
         )
 
+        slow_delete(
+            OutgoingMail.objects.filter(event=self.event)
+        )
+
         for o in _progress_helper(qs_orders, progress_callback, qs_op_cnt, total):
             changed = bool(o.email) or bool(o.customer)
             o.email = None