Email: Allow to override backend for custom SMTP connections (#2368)

src/pretix/base/email.py

@@ -25,6 +25,7 @@ from datetime import timedelta
 from decimal import Decimal
 from itertools import groupby
 from smtplib import SMTPResponseException
+from typing import TypeVar
 
 import css_inline
 from django.conf import settings
@@ -49,23 +50,23 @@ from pretix.base.templatetags.rich_text import markdown_compile_email
 
 logger = logging.getLogger('pretix.base.email')
 
+T = TypeVar("T", bound=EmailBackend)
 
-class CustomSMTPBackend(EmailBackend):
 
-    def test(self, from_addr):
-        try:
-            self.open()
-            self.connection.ehlo_or_helo_if_needed()
-            (code, resp) = self.connection.mail(from_addr, [])
-            if code != 250:
-                logger.warn('Error testing mail settings, code %d, resp: %s' % (code, resp))
-                raise SMTPResponseException(code, resp)
-            (code, resp) = self.connection.rcpt('testdummy@pretix.eu')
-            if (code != 250) and (code != 251):
-                logger.warn('Error testing mail settings, code %d, resp: %s' % (code, resp))
-                raise SMTPResponseException(code, resp)
-        finally:
-            self.close()
+def test_custom_smtp_backend(backend: T, from_addr: str) -> None:
+    try:
+        backend.open()
+        backend.connection.ehlo_or_helo_if_needed()
+        (code, resp) = backend.connection.mail(from_addr, [])
+        if code != 250:
+            logger.warning('Error testing mail settings, code %d, resp: %s' % (code, resp))
+            raise SMTPResponseException(code, resp)
+        (code, resp) = backend.connection.rcpt('testdummy@pretix.eu')
+        if (code != 250) and (code != 251):
+            logger.warning('Error testing mail settings, code %d, resp: %s' % (code, resp))
+            raise SMTPResponseException(code, resp)
+    finally:
+        backend.close()
 
 
 class BaseHTMLMailRenderer:

src/pretix/base/models/event.py

@@ -670,16 +670,17 @@ class Event(EventMixin, LoggedModel):
         Returns an email server connection, either by using the system-wide connection
         or by returning a custom one based on the event's settings.
         """
-        from pretix.base.email import CustomSMTPBackend
 
         if self.settings.smtp_use_custom or force_custom:
-            return CustomSMTPBackend(host=self.settings.smtp_host,
-                                     port=self.settings.smtp_port,
-                                     username=self.settings.smtp_username,
-                                     password=self.settings.smtp_password,
-                                     use_tls=self.settings.smtp_use_tls,
-                                     use_ssl=self.settings.smtp_use_ssl,
-                                     fail_silently=False, timeout=timeout)
+            return get_connection(backend=settings.EMAIL_CUSTOM_SMTP_BACKEND,
+                                  host=self.settings.smtp_host,
+                                  port=self.settings.smtp_port,
+                                  username=self.settings.smtp_username,
+                                  password=self.settings.smtp_password,
+                                  use_tls=self.settings.smtp_use_tls,
+                                  use_ssl=self.settings.smtp_use_ssl,
+                                  fail_silently=False,
+                                  timeout=timeout)
         else:
             return get_connection(fail_silently=False)
 

src/pretix/base/models/organizer.py

@@ -36,6 +36,7 @@ import string
 from datetime import date, datetime, time
 
 import pytz
+from django.conf import settings
 from django.core.mail import get_connection
 from django.core.validators import MinLengthValidator, RegexValidator
 from django.db import models
@@ -195,16 +196,15 @@ class Organizer(LoggedModel):
         Returns an email server connection, either by using the system-wide connection
         or by returning a custom one based on the organizer's settings.
         """
-        from pretix.base.email import CustomSMTPBackend
-
         if self.settings.smtp_use_custom or force_custom:
-            return CustomSMTPBackend(host=self.settings.smtp_host,
-                                     port=self.settings.smtp_port,
-                                     username=self.settings.smtp_username,
-                                     password=self.settings.smtp_password,
-                                     use_tls=self.settings.smtp_use_tls,
-                                     use_ssl=self.settings.smtp_use_ssl,
-                                     fail_silently=False, timeout=timeout)
+            return get_connection(backend=settings.EMAIL_CUSTOM_SMTP_BACKEND,
+                                  host=self.settings.smtp_host,
+                                  port=self.settings.smtp_port,
+                                  username=self.settings.smtp_username,
+                                  password=self.settings.smtp_password,
+                                  use_tls=self.settings.smtp_use_tls,
+                                  use_ssl=self.settings.smtp_use_ssl,
+                                  fail_silently=False, timeout=timeout)
         else:
             return get_connection(fail_silently=False)
 

src/pretix/control/views/event.py

@@ -65,7 +65,9 @@ from i18nfield.utils import I18nJSONEncoder
 from pytz import timezone
 
 from pretix.base.channels import get_all_sales_channels
-from pretix.base.email import get_available_placeholders
+from pretix.base.email import (
+    get_available_placeholders, test_custom_smtp_backend,
+)
 from pretix.base.models import Event, LogEntry, Order, TaxRule, Voucher
 from pretix.base.models.event import EventMetaValue
 from pretix.base.services import tickets
@@ -641,7 +643,7 @@ class MailSettings(EventSettingsViewMixin, EventSettingsFormView):
             if request.POST.get('test', '0').strip() == '1':
                 backend = self.request.event.get_mail_backend(force_custom=True, timeout=10)
                 try:
-                    backend.test(self.request.event.settings.mail_from)
+                    test_custom_smtp_backend(backend, self.request.event.settings.mail_from)
                 except Exception as e:
                     messages.warning(self.request, _('An error occurred while contacting the SMTP server: %s') % str(e))
                 else:

src/pretix/control/views/organizer.py

@@ -64,6 +64,7 @@ from django.views.generic import (
 from pretix.api.models import WebHook
 from pretix.base.auth import get_auth_backends
 from pretix.base.channels import get_all_sales_channels
+from pretix.base.email import test_custom_smtp_backend
 from pretix.base.i18n import language
 from pretix.base.models import (
     CachedFile, Customer, Device, Gate, GiftCard, Invoice, LogEntry,
@@ -265,7 +266,7 @@ class OrganizerMailSettings(OrganizerSettingsFormView):
             if request.POST.get('test', '0').strip() == '1':
                 backend = self.request.organizer.get_mail_backend(force_custom=True, timeout=10)
                 try:
-                    backend.test(self.request.organizer.settings.mail_from)
+                    test_custom_smtp_backend(backend, self.request.organizer.settings.mail_from)
                 except Exception as e:
                     messages.warning(self.request, _('An error occurred while contacting the SMTP server: %s') % str(e))
                 else:

src/pretix/settings.py

@@ -222,6 +222,7 @@ EMAIL_HOST_PASSWORD = config.get('mail', 'password', fallback='')
 EMAIL_USE_TLS = config.getboolean('mail', 'tls', fallback=False)
 EMAIL_USE_SSL = config.getboolean('mail', 'ssl', fallback=False)
 EMAIL_SUBJECT_PREFIX = '[pretix] '
+EMAIL_BACKEND = EMAIL_CUSTOM_SMTP_BACKEND = 'django.core.mail.backends.smtp.EmailBackend'
 
 ADMINS = [('Admin', n) for n in config.get('mail', 'admins', fallback='').split(",") if n]
 

src/pretix/testutils/settings.py

@@ -37,7 +37,7 @@ SITE_URL = "http://example.com"
 
 atexit.register(tmpdir.cleanup)
 
-EMAIL_BACKEND = 'django.core.mail.backends.locmem.EmailBackend'
+EMAIL_BACKEND = EMAIL_CUSTOM_SMTP_BACKEND = 'django.core.mail.backends.locmem.EmailBackend'
 
 COMPRESS_ENABLED = COMPRESS_OFFLINE = False
 COMPRESS_CACHE_BACKEND = 'testcache'