+EMAIL_QUEUE_DISCARD_HOURS +EMAIL_QUEUE_RETRY_SECONDS

src/django_email_queue/app_settings.py

@@ -16,3 +16,9 @@
 
 #: Sleep time between queue checkup
 EMAIL_QUEUE_SLEEP_TIME = 15
+
+#: Discard messages after failing delivery for X hours
+EMAIL_QUEUE_DISCARD_HOURS = None
+
+#: Retry stalled messages (status==sending) after X seconds
+EMAIL_QUEUE_RETRY_SECONDS = 300

src/django_email_queue/migrations/0003_auto_20180504_0956.py

@@ -0,0 +1,24 @@
+# Generated by Django 2.0.3 on 2018-05-04 09:56
+
+from django.db import migrations, models
+import django_email_queue.models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('django_email_queue', '0002_auto_20180412_1413'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='queuedemailmessage',
+            name='ts',
+            field=models.DateTimeField(auto_now=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='queuedemailmessage',
+            name='status',
+            field=models.PositiveSmallIntegerField(choices=[(0, 'Created'), (1, 'Posted'), (2, 'Sending'), (3, 'Discarded')], default=django_email_queue.models.QueuedEmailMessageStatus(0)),
+        ),
+    ]

src/django_email_queue/models.py

@@ -4,12 +4,14 @@
 from __future__ import absolute_import, unicode_literals
 
 import logging
+from datetime import timedelta
 from enum import IntEnum
 
 import six
 from django.conf import settings
 from django.core.mail.message import EmailMultiAlternatives
 from django.db import models
+from django.db.models import Q
 from django.utils import timezone
 from django.utils.translation import ugettext_lazy as _
 
@@ -30,6 +32,7 @@ class QueuedEmailMessageStatus(ChoicesIntEnum):
     created = 0
     posted = 1
     sending = 2
+    discarded = 3
 
 
 HTML_MIME_TYPE = 'text/html'
@@ -41,6 +44,7 @@ class QueuedEmailMessage(models.Model):
     status = models.PositiveSmallIntegerField(choices=QueuedEmailMessageStatus.choices(), default=QueuedEmailMessageStatus.created)
     created = models.DateTimeField(auto_now_add=True)
     posted = models.DateTimeField(blank=True, null=True)
+    ts = models.DateTimeField(blank=True, null=True, auto_now=True)
     encoding = models.CharField(max_length=15, blank=True, null=True)
     from_email = models.CharField(max_length=300)
     to = models.TextField(blank=True, null=True)
@@ -90,7 +94,20 @@ def queue(cls, email_messages):
             logging.debug("Queue message: %s", instance)
             yield instance
 
-    def send(self, connection=None, fail_silently=False):
+    def send(self, connection=None, fail_silently=True):
+        try:
+            return self._send(connection=connection, fail_silently=False)
+        except Exception as ex:
+            if fail_silently is False:
+                raise ex
+            # Log error but do not block other messages
+            logging.error("Email send failed", exc_info=ex)
+            age_hours = (timezone.now() - self.created).seconds / 3600
+            if settings.EMAIL_QUEUE_DISCARD_HOURS and age_hours > settings.EMAIL_QUEUE_DISCARD_HOURS:
+                self.status = QueuedEmailMessageStatus.discarded
+                self.save()
+
+    def _send(self, connection=None, fail_silently=False):
         if connection is None:
             from django.core.mail import get_connection
             connection = get_connection(
@@ -125,7 +142,12 @@ def send(self, connection=None, fail_silently=False):
 
     @classmethod
     def send_queued(cls, limit=None):
-        qry = cls.objects.filter(status=QueuedEmailMessageStatus.created).order_by("created")
+        seconds = settings.EMAIL_QUEUE_RETRY_SECONDS
+        retry = timezone.now() - timedelta(seconds=seconds)
+        qry = cls.objects.filter(
+            Q(status=QueuedEmailMessageStatus.created) |
+            Q(status=QueuedEmailMessageStatus.sending, ts__lte=retry)
+        ).order_by("created")
         if limit:
             qry = qry[:limit]
         cls.bulk_send(qry)

tests/test_backend.py

@@ -4,6 +4,7 @@
 from __future__ import absolute_import, unicode_literals
 
 import os
+from datetime import timedelta
 
 import pytest
 import six
@@ -18,6 +19,7 @@
 from django_email_queue import backends, models
 from django_email_queue.admin import QueuedEmailMessageAdmin
 from django_email_queue.models import QueuedEmailMessage, QueuedEmailMessageStatus
+from tests import factories
 from tests.factories import QueuedEmailMessageFactory
 
 
@@ -123,10 +125,72 @@ def test_str(self):
         o = QueuedEmailMessage(subject="ążśźćń󳥯ŚŹĘĆŃÓŁ", to="b")
         self.assertEqual(u"QueuedEmailMessage:ążśźćń󳥯ŚŹĘĆŃÓŁ:b", six.text_type(o))
 
+    @override_settings(EMAIL_QUEUE_DISCARD_HOURS=2)
+    @patch('django_email_queue.models.QueuedEmailMessage._send')
+    def test_discard_message(self, send):
+        send.side_effect = Exception("Foo")
+        item = models.QueuedEmailMessage(created=timezone.now() - timedelta(hours=2, seconds=1))
+        item.send()
+        self.assertEqual(item.status, models.QueuedEmailMessageStatus.discarded)
+
+    @override_settings(EMAIL_QUEUE_DISCARD_HOURS=1)
+    @patch('django_email_queue.models.QueuedEmailMessage._send')
+    def test_dont_discard_message(self, send):
+        send.side_effect = Exception("Foo")
+        item = models.QueuedEmailMessage(created=timezone.now() - timedelta(seconds=3599))
+        item.send()
+        self.assertEqual(models.QueuedEmailMessageStatus.created, item.status)
+
+    @override_settings(EMAIL_QUEUE_DISCARD_HOURS=None)
+    @patch('django_email_queue.models.QueuedEmailMessage._send')
+    def test_dont_discard_message2(self, send):
+        send.side_effect = Exception("Foo")
+        item = models.QueuedEmailMessage(created=timezone.now() - timedelta(seconds=3599))
+        item.send()
+        self.assertEqual(models.QueuedEmailMessageStatus.created, item.status)
+
+    @patch('django_email_queue.models.QueuedEmailMessage._send')
+    def test_fail_silently(self, send):
+        send.side_effect = Exception("Foo")
+        item = models.QueuedEmailMessage(created=timezone.now())
+        item.send()
+
+    @patch('django_email_queue.models.QueuedEmailMessage._send')
+    def test_dont_fail_silently(self, send):
+        send.side_effect = Exception("Foo")
+        item = models.QueuedEmailMessage()
+        self.assertRaises(Exception, item.send, fail_silently=False)
+
+    @override_settings(EMAIL_QUEUE_RETRY_SECONDS=600)
+    @patch('django_email_queue.models.QueuedEmailMessage._send')
+    def test_retry_busy(self, send):
+        seconds = settings.EMAIL_QUEUE_RETRY_SECONDS + 2
+        retry = timezone.now() - timedelta(seconds=seconds)
+        message = factories.QueuedEmailMessageFactory(
+            ts=retry,
+            status=models.QueuedEmailMessageStatus.sending,
+        )
+        models.QueuedEmailMessage.objects.all().update(ts=retry)
+        message.send_queued()
+        self.assertTrue(send.called)
+
+    @override_settings(EMAIL_QUEUE_RETRY_SECONDS=600)
+    @patch('django_email_queue.models.QueuedEmailMessage._send')
+    def test_retry_wait(self, send):
+        seconds = settings.EMAIL_QUEUE_RETRY_SECONDS - 2
+        retry = timezone.now() - timedelta(seconds=seconds)
+        message = factories.QueuedEmailMessageFactory(
+            ts=retry,
+            status=models.QueuedEmailMessageStatus.sending,
+        )
+        models.QueuedEmailMessage.objects.all().update(ts=retry)
+        message.send_queued()
+        self.assertFalse(send.called)
+
 
 class QueuedEmailMessageStatusTests(TestCase):
     def test_values(self):
-        self.assertEqual([0, 1, 2], QueuedEmailMessageStatus.values())
+        self.assertEqual([0, 1, 2, 3], QueuedEmailMessageStatus.values())
 
 
 class CommandTests(TestCase):