Email debug flag (fixes #3526)

DEVELOPMENT.rst

@@ -83,6 +83,10 @@ windows run::
 
     $ python manage.py start --no-browser
 
+When debugging something email related change the email backend to console::
+
+    $ python manage.py start --debug-email
+
 To start OpenSlides with Daphne and four workers (avoid concurrent write
 requests or use PostgreSQL, see below) run::
 

openslides/__main__.py

@@ -107,6 +107,10 @@ def get_parser():
         '--no-browser',
         action='store_true',
         help='Do not launch the default web browser.')
+    subcommand_start.add_argument(
+        '--debug-email',
+        action='store_true',
+        help='Change the email backend to console output.')
     subcommand_start.add_argument(
         '--host',
         action='store',
@@ -188,6 +192,9 @@ def start(args):
     django.setup()
     from django.conf import settings
 
+    if args.debug_email:
+        settings.EMAIL_BACKEND = 'django.core.mail.backends.console.EmailBackend'
+
     # Migrate database
     call_command('migrate')