Fix sendmail migration activating plugin on events (#6656)

pyproject.toml

@@ -34,7 +34,7 @@ dependencies = [
   "celery==5.6.*",
   "chardet==5.2.*",
   "cryptography>=50.0.2",
-  "css-inline==0.22.*",
+  "css-inline==0.21.*",
   "defusedcsv>=3.0.0",
   "dnspython==2.*",
   "Django[argon2]==5.2.*,>=5.2.17",

src/pretix/base/services/notifications.py

@@ -172,10 +172,11 @@ def send_notification_mail(notification: Notification, user: User):
     guid = uuid.uuid4()
     settings_holder = notification.event or notification.organizer
     prefix = settings_holder.settings.mail_prefix
-    if not prefix and notification.event:
-        prefix = notification.event.slug.upper()
-    elif notification.organizer:
-        prefix = notification.organizer.name
+    if not prefix:
+        if notification.event:
+            prefix = notification.event.slug.upper()
+        elif notification.organizer:
+            prefix = notification.organizer.name
     m = OutgoingMail.objects.create(
         guid=guid,
         user=user,

src/pretix/plugins/sendmail/migrations/0013_activate_plugin_for_events_with_scheduled_mails.py

@@ -19,7 +19,9 @@ def activate_plugin(apps, schema_editor):
     )
 
     for event in events:
-        event.enable_plugin('pretix.plugins.sendmail')
+        plugins_active = event.plugins.split(',')
+        plugins_active.append('pretix.plugins.sendmail')
+        event.plugins = ','.join(plugins_active)
         event.save(update_fields=['plugins'])