let create_transactions() handle all the mailing

src/pretix/api/serializers/order.py

@@ -1819,7 +1819,7 @@ class OrderCreateSerializer(I18nAwareModelSerializer):
                         },
                         state=OrderPayment.PAYMENT_STATE_CREATED
                     )
-                    gift_card_payment_provider.execute_payment(request=None, payment=payment, is_early_special_case=not self._send_mail)
+                    gift_card_payment_provider.execute_payment(request=None, payment=payment, is_early_special_case=True)
 
                     if order.pending_sum <= Decimal('0.00'):
                         order.status = Order.STATUS_PAID

src/pretix/base/payment.py

@@ -1657,7 +1657,7 @@ class GiftCardPayment(BasePaymentProvider):
                     }
                 )
         except PaymentException as e:
-            payment.fail(info={'error': str(e)})
+            payment.fail(info={'error': str(e)}, send_mail=not is_early_special_case)
             raise e
 
     def payment_is_valid_session(self, request: HttpRequest) -> bool:

src/tests/api/test_order_create.py

@@ -3420,7 +3420,7 @@ def test_order_create_use_gift_cards_only_pending(token_client, organizer, event
             False, 0
         ),
         (
-            True, 2  # TODO check why we get 3 mails, one order receivend and two payments
+            True, 2
         ),
     ],
 )