diff --git a/.coveragerc b/.coveragerc
index 166c774..4a530cf 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -1,6 +1,7 @@
 [run]
 omit =
     project/celery.py
+    project/base_tasks.py
     project/celery_tasks.py
     project/cli/test.py
     project/templates/email/*
\ No newline at end of file
diff --git a/README.md b/README.md
index e72a3b7..090ee8f 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# Open Event Database
+# EventCally - Open event calendar
 
 ![Tests](https://github.com/eventcally/eventcally/workflows/Tests/badge.svg) [![codecov](https://codecov.io/gh/eventcally/eventcally/branch/main/graph/badge.svg?token=66CLLWWV7Y)](https://codecov.io/gh/eventcally/eventcally) [![Cypress](https://img.shields.io/endpoint?url=https://dashboard.cypress.io/badge/simple/32g194/main&style=flat&logo=cypress)](https://dashboard.cypress.io/projects/32g194/runs) [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black) [![Docker Pulls](https://img.shields.io/docker/pulls/eventcally/eventcally)](https://hub.docker.com/r/eventcally/eventcally)
 
diff --git a/deployment/docker-compose/docker-compose.yml b/deployment/docker-compose/docker-compose.yml
index ce20ce9..12deda4 100644
--- a/deployment/docker-compose/docker-compose.yml
+++ b/deployment/docker-compose/docker-compose.yml
@@ -24,6 +24,7 @@ x-web-env:
   JWT_PRIVATE_KEY: ${JWT_PRIVATE_KEY}
   JWT_PUBLIC_JWKS: ${JWT_PUBLIC_JWKS}
   DOCS_URL: ${DOCS_URL}
+  SITE_NAME: ${SITE_NAME}
 
 x-web:
   &default-web
diff --git a/messages.pot b/messages.pot
index 982956a..3306229 100644
--- a/messages.pot
+++ b/messages.pot
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PROJECT VERSION\n"
 "Report-Msgid-Bugs-To: EMAIL@ADDRESS\n"
-"POT-Creation-Date: 2023-03-16 19:11+0100\n"
+"POT-Creation-Date: 2023-03-24 21:24+0100\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -198,93 +198,101 @@ msgstr ""
 msgid "You have received an invitation"
 msgstr ""
 
-#: project/forms/admin.py:10 project/templates/layout.html:294
-#: project/views/root.py:57
+#: project/forms/admin.py:11 project/templates/layout.html:294
+#: project/views/root.py:53
 msgid "Terms of service"
 msgstr ""
 
-#: project/forms/admin.py:11 project/templates/layout.html:298
-#: project/views/root.py:65
+#: project/forms/admin.py:12 project/templates/layout.html:298
+#: project/views/root.py:61
 msgid "Legal notice"
 msgstr ""
 
-#: project/forms/admin.py:12 project/templates/_macros.html:1395
+#: project/forms/admin.py:13 project/templates/_macros.html:1395
 #: project/templates/layout.html:302
 #: project/templates/widget/event_suggestion/create.html:204
-#: project/views/admin_unit.py:73 project/views/root.py:73
+#: project/views/admin_unit.py:73 project/views/root.py:69
 msgid "Contact"
 msgstr ""
 
-#: project/forms/admin.py:13 project/templates/layout.html:306
-#: project/views/root.py:81
+#: project/forms/admin.py:14 project/templates/layout.html:306
+#: project/views/root.py:77
 msgid "Privacy"
 msgstr ""
 
-#: project/forms/admin.py:14
+#: project/forms/admin.py:15
 msgid "Start page"
 msgstr ""
 
-#: project/forms/admin.py:16 project/forms/oauth2_client.py:24
+#: project/forms/admin.py:17 project/forms/oauth2_client.py:24
 msgid "Save"
 msgstr ""
 
-#: project/forms/admin.py:20 project/forms/admin_unit_member.py:12
+#: project/forms/admin.py:21 project/forms/admin_unit_member.py:12
 #: project/forms/admin_unit_member.py:32
 msgid "Roles"
 msgstr ""
 
-#: project/forms/admin.py:21 project/templates/admin/update_user.html:4
+#: project/forms/admin.py:22 project/templates/admin/update_user.html:4
 #: project/templates/admin/update_user.html:8
 msgid "Update user"
 msgstr ""
 
-#: project/forms/admin.py:26
+#: project/forms/admin.py:27
 msgid "Incoming reference requests allowed"
 msgstr ""
 
-#: project/forms/admin.py:27
+#: project/forms/admin.py:28
 msgid ""
 "If set, other organizations can ask this organization to reference their "
 "event."
 msgstr ""
 
-#: project/forms/admin.py:33
+#: project/forms/admin.py:34
 msgid "Suggestions enabled"
 msgstr ""
 
-#: project/forms/admin.py:34
+#: project/forms/admin.py:35
 msgid "If set, the organization can work with suggestions."
 msgstr ""
 
-#: project/forms/admin.py:38
+#: project/forms/admin.py:39
 msgid "Create other organizations"
 msgstr ""
 
-#: project/forms/admin.py:39
+#: project/forms/admin.py:40
 msgid "If set, members of the organization can create other organizations."
 msgstr ""
 
-#: project/forms/admin.py:45
+#: project/forms/admin.py:46
 msgid "Invite other organizations"
 msgstr ""
 
-#: project/forms/admin.py:46
+#: project/forms/admin.py:47
 msgid "If set, members of the organization can invite other organizations."
 msgstr ""
 
-#: project/forms/admin.py:52
+#: project/forms/admin.py:53
 msgid "Verify other organizations"
 msgstr ""
 
-#: project/forms/admin.py:53
+#: project/forms/admin.py:54
 msgid "If set, members of the organization can verify other organizations."
 msgstr ""
 
-#: project/forms/admin.py:58 project/templates/admin/update_admin_unit.html:4
+#: project/forms/admin.py:59 project/templates/admin/update_admin_unit.html:4
 #: project/templates/admin/update_admin_unit.html:8
 msgid "Update organization"
 msgstr ""
 
+#: project/forms/admin.py:63
+msgid "Recipient"
+msgstr ""
+
+#: project/forms/admin.py:65
+msgid "Send test mail synchronously"
+msgstr ""
+
 #: project/forms/admin_unit.py:15 project/forms/event_place.py:12
 #: project/forms/organizer.py:12
 msgid "Street"
@@ -348,7 +356,8 @@ msgstr ""
 #: project/forms/admin_unit_member.py:23 project/forms/admin_unit_member.py:28
 #: project/forms/event.py:107 project/forms/event_suggestion.py:38
 #: project/forms/organizer.py:27 project/templates/_macros.html:235
-#: project/templates/_macros.html:1491 project/templates/admin/users.html:19
+#: project/templates/_macros.html:1491 project/templates/admin/admin.html:27
+#: project/templates/admin/users.html:19
 msgid "Email"
 msgstr ""
 
@@ -1365,15 +1374,10 @@ msgstr ""
 msgid "Enter list name"
 msgstr ""
 
-#: project/templates/home.html:27
+#: project/templates/home.html:24
 msgid "Manage"
 msgstr ""
 
-#: project/templates/home.html:29 project/templates/security/login_user.html:38
-#: project/views/widget.py:159
-msgid "Register for free"
-msgstr ""
-
 #: project/templates/layout.html:152 project/templates/layout.html:200
 #: project/templates/manage/events.html:6
 #: project/templates/manage/events.html:42
@@ -1409,6 +1413,8 @@ msgstr ""
 
 #: project/templates/admin/admin.html:3 project/templates/admin/admin.html:9
 #: project/templates/admin/admin_units.html:10
+#: project/templates/admin/email.html:65
+#: project/templates/admin/settings.html:10
 #: project/templates/admin/users.html:10 project/templates/layout.html:171
 msgid "Admin"
 msgstr ""
@@ -1495,9 +1501,10 @@ msgstr ""
 msgid "Organization invitations"
 msgstr ""
 
-#: project/templates/admin/admin.html:15
+#: project/templates/admin/admin.html:15 project/templates/admin/email.html:4
+#: project/templates/admin/email.html:66
 #: project/templates/admin/settings.html:4
-#: project/templates/admin/settings.html:8
+#: project/templates/admin/settings.html:11
 #: project/templates/admin_unit/update.html:6
 #: project/templates/admin_unit/update.html:23
 #: project/templates/layout.html:253 project/templates/manage/widgets.html:11
@@ -1553,6 +1560,18 @@ msgstr ""
 msgid "Edit"
 msgstr ""
 
+#: project/templates/admin/email.html:47 project/views/admin.py:119
+msgid "Mail sent successfully"
+msgstr ""
+
+#: project/templates/admin/email.html:103
+msgid "Test mail"
+msgstr ""
+
+#: project/templates/admin/email.html:111
+msgid "Send test mail asynchronously"
+msgstr ""
+
 #: project/templates/admin_unit/create.html:58
 #: project/templates/admin_unit/update.html:59
 #: project/templates/event/create.html:347
@@ -1665,6 +1684,14 @@ msgstr ""
 msgid "The review status of your event has been updated."
 msgstr ""
 
+#: project/templates/email/test_email.html:4
+msgid "This is a test mail"
+msgstr ""
+
+#: project/templates/email/test_email.html:5
+msgid "Click here to open the site"
+msgstr ""
+
 #: project/templates/event/actions.html:5
 #: project/templates/event/actions.html:22
 msgid "Actions for event"
@@ -1984,6 +2011,10 @@ msgstr ""
 msgid "You do not have an account yet? Not a problem!"
 msgstr ""
 
+#: project/templates/security/login_user.html:38 project/views/widget.py:159
+msgid "Register for free"
+msgstr ""
+
 #: project/templates/widget/event_date/list.html:5
 msgid "Widget"
 msgstr ""
@@ -2004,15 +2035,20 @@ msgstr ""
 msgid "Preview"
 msgstr ""
 
-#: project/views/admin.py:44
+#: project/views/admin.py:55
 msgid "Organization successfully updated"
 msgstr ""
 
-#: project/views/admin.py:68 project/views/manage.py:361
+#: project/views/admin.py:79 project/views/manage.py:361
 msgid "Settings successfully updated"
 msgstr ""
 
-#: project/views/admin.py:103
+#: project/views/admin.py:108
+#, python-format
+msgid "Test mail from %(site_name)s"
+msgstr ""
+
+#: project/views/admin.py:152
 msgid "User successfully updated"
 msgstr ""
 
diff --git a/project/__init__.py b/project/__init__.py
index 503c8d4..a4ac6de 100644
--- a/project/__init__.py
+++ b/project/__init__.py
@@ -16,10 +16,18 @@ from flask_wtf.csrf import CSRFProtect
 from project.custom_session_interface import CustomSessionInterface
 
 
-def getenv_bool(name: str, default: str = "False"):  # pragma: no cover
+def getenv_bool(name: str, default: str = "False"):
     return os.getenv(name, default).lower() in ("true", "1", "t")
 
 
+def set_env_to_app(app: Flask, key: str, default: str = None):
+    if key in os.environ and os.environ[key]:  # pragma: no cover
+        app.config[key] = os.environ[key]
+
+    if default:
+        app.config[key] = default
+
+
 # Create app
 app = Flask(__name__)
 app.config["SQLALCHEMY_DATABASE_URI"] = os.environ["DATABASE_URL"]
@@ -34,7 +42,6 @@ app.config["SECURITY_RECOVERABLE"] = True
 app.config["SECURITY_CHANGEABLE"] = True
 app.config["SECURITY_EMAIL_SENDER"] = os.getenv("MAIL_DEFAULT_SENDER")
 app.config["LANGUAGES"] = ["en", "de"]
-app.config["SITE_NAME"] = os.getenv("SITE_NAME", "eventcally")
 app.config["SERVER_NAME"] = os.getenv("SERVER_NAME")
 app.config["DOCS_URL"] = os.getenv("DOCS_URL")
 app.config["ADMIN_UNIT_CREATE_REQUIRES_ADMIN"] = os.getenv(
@@ -42,6 +49,7 @@ app.config["ADMIN_UNIT_CREATE_REQUIRES_ADMIN"] = os.getenv(
 )
 app.config["SEO_SITEMAP_PING_GOOGLE"] = getenv_bool("SEO_SITEMAP_PING_GOOGLE", "False")
 app.config["GOOGLE_MAPS_API_KEY"] = os.getenv("GOOGLE_MAPS_API_KEY")
+set_env_to_app(app, "SITE_NAME", "EventCally")
 
 # Proxy handling
 if os.getenv("PREFERRED_URL_SCHEME"):  # pragma: no cover
@@ -58,11 +66,8 @@ app.config.update(
         "broker_url": app.config["REDIS_URL"],
         "result_backend": app.config["REDIS_URL"],
         "result_expires": timedelta(hours=1),
-        "broker_pool_limit": None,
-        "redis_max_connections": 2,
         "timezone": "Europe/Berlin",
         "broker_transport_options": {
-            "max_connections": 2,
             "queue_order_strategy": "priority",
             "priority_steps": list(range(3)),
             "sep": ":",
diff --git a/project/base_tasks.py b/project/base_tasks.py
new file mode 100644
index 0000000..f29caf7
--- /dev/null
+++ b/project/base_tasks.py
@@ -0,0 +1,10 @@
+from project import app, celery
+from project.views.utils import send_mail
+
+
+@celery.task(
+    base=getattr(app, "celery_http_task_cls"),
+    priority=0,
+)
+def send_mail_task(recipient, subject, template):
+    send_mail(recipient, subject, template)
diff --git a/project/celery.py b/project/celery.py
index 980fa30..e4b6a4a 100644
--- a/project/celery.py
+++ b/project/celery.py
@@ -2,13 +2,8 @@ from smtplib import SMTPException
 from urllib.error import URLError
 
 from celery import Celery
-from celery.signals import (
-    after_setup_logger,
-    after_setup_task_logger,
-    task_postrun,
-    worker_ready,
-)
-from celery_singleton import Singleton, clear_locks
+from celery import Task as BaseTask
+from celery.signals import after_setup_logger, after_setup_task_logger, task_postrun
 from requests.exceptions import RequestException
 
 
@@ -19,7 +14,7 @@ class HttpTaskException(Exception):
 def create_celery(app):
     celery = Celery(app.import_name)
     celery.conf.update(app.config["CELERY_CONFIG"])
-    TaskBase = Singleton
+    TaskBase = BaseTask
 
     class ContextTask(TaskBase):
         abstract = True
@@ -71,13 +66,6 @@ def setup_task_logger(logger, *args, **kwargs):
     init_logger_with_one_line_formatter(logger)
 
 
-@worker_ready.connect
-def unlock_all(**kwargs):
-    from project import celery
-
-    clear_locks(celery)
-
-
 @task_postrun.connect
 def close_session(*args, **kwargs):
     from project import app
diff --git a/project/forms/admin.py b/project/forms/admin.py
index 4898be8..e7251f3 100644
--- a/project/forms/admin.py
+++ b/project/forms/admin.py
@@ -1,7 +1,8 @@
 from flask_babelex import lazy_gettext
 from flask_wtf import FlaskForm
 from wtforms import BooleanField, SubmitField, TextAreaField
-from wtforms.validators import Optional
+from wtforms.fields.html5 import EmailField
+from wtforms.validators import DataRequired, Optional
 
 from project.forms.widgets import MultiCheckboxField
 
@@ -56,3 +57,9 @@ class UpdateAdminUnitForm(FlaskForm):
         validators=[Optional()],
     )
     submit = SubmitField(lazy_gettext("Update organization"))
+
+
+class AdminTestEmailForm(FlaskForm):
+    recipient = EmailField(lazy_gettext("Recipient"), validators=[DataRequired()])
+
+    submit = SubmitField(lazy_gettext("Send test mail synchronously"))
diff --git a/project/jinja_filters.py b/project/jinja_filters.py
index 5e61af1..484e70f 100644
--- a/project/jinja_filters.py
+++ b/project/jinja_filters.py
@@ -26,6 +26,9 @@ def any_dict_value_true(data: dict):
 
 
 def ensure_link_scheme(link: str):
+    if not link:  # pragma: no cover
+        return link
+
     if link.startswith("http://") or link.startswith("https://"):
         return link
 
diff --git a/project/templates/admin/admin.html b/project/templates/admin/admin.html
index 8e096a5..024b0e1 100644
--- a/project/templates/admin/admin.html
+++ b/project/templates/admin/admin.html
@@ -23,6 +23,10 @@
         {{ _('Users') }}
         <i class="fa fa-caret-right"></i>
     </a>
+    <a href="{{ url_for('admin_email') }}" class="list-group-item">
+        {{ _('Email') }}
+        <i class="fa fa-caret-right"></i>
+    </a>
 </div>
 
 {% endblock %}
\ No newline at end of file
diff --git a/project/templates/admin/email.html b/project/templates/admin/email.html
new file mode 100644
index 0000000..88ad55c
--- /dev/null
+++ b/project/templates/admin/email.html
@@ -0,0 +1,124 @@
+{% extends "layout.html" %}
+{% from "_macros.html" import render_field, render_field_with_errors %}
+{%- block title -%}
+{{ _('Settings') }}
+{%- endblock -%}
+{% block header %}
+<script>
+    function submit_async() {
+        handle_request_start();
+        $.ajax({
+            url: "{{ url_for('admin_email', async=1) }}",
+            type: "post",
+            dataType: "json",
+            data: $("#test_mail_form").serialize(),
+            error: function(xhr, status, error) {
+                handle_request_error(xhr, status, error);
+            },
+            success: function (data) {
+                poll(data["result_id"]);
+            }
+        });
+    }
+
+    function poll(result_id) {
+        $.ajax({
+            url: "{{ url_for('admin_email') }}",
+            type: "get",
+            dataType: "json",
+            data: "poll=" + result_id,
+            error: function(xhr, status, error) {
+                handle_request_error(xhr, status, error);
+            },
+            success: function (data) {
+                if (!data["ready"]) {
+                    setTimeout(function() {
+                        poll(result_id);
+                    }, 500);
+                    return;
+                }
+
+                if (!data["successful"]) {
+                  console.error(data);
+                  handle_request_error(null, JSON.stringify(data), data);
+                  return;
+                }
+
+                $("#result_container").text("{{ _('Mail sent successfully') }}");
+                handle_request_success();
+            }
+        });
+    }
+
+    $( function() {
+        $("#submit_async").click(function(){
+            submit_async();
+            return false;
+        });
+    });
+</script>
+{% endblock %}
+{% block content %}
+
+<nav aria-label="breadcrumb">
+    <ol class="breadcrumb">
+        <li class="breadcrumb-item"><a href="{{ url_for('admin') }}">{{ _('Admin') }}</a></li>
+        <li class="breadcrumb-item active" aria-current="page">{{ _('Settings') }}</li>
+    </ol>
+</nav>
+
+<table class="table table-striped table-bordered my-4">
+    <tbody>
+        <tr>
+            <td>MAIL_SUPPRESS_SEND</td>
+            <td>{{ config["MAIL_SUPPRESS_SEND"] }}</td>
+        </tr>
+        <tr>
+            <td>MAIL_SERVER</td>
+            <td>{{ config["MAIL_SERVER"] }}</td>
+        </tr>
+        <tr>
+            <td>MAIL_PORT</td>
+            <td>{{ config["MAIL_PORT"] }}</td>
+        </tr>
+        <tr>
+            <td>MAIL_USE_TLS</td>
+            <td>{{ config["MAIL_USE_TLS"] }}</td>
+        </tr>
+        <tr>
+            <td>MAIL_USE_SSL</td>
+            <td>{{ config["MAIL_USE_SSL"] }}</td>
+        </tr>
+        <tr>
+            <td>MAIL_USERNAME</td>
+            <td>{{ config["MAIL_USERNAME"] }}</td>
+        </tr>
+        <tr>
+            <td>MAIL_PASSWORD</td>
+            <td>{{ config["MAIL_PASSWORD"] }}</td>
+        </tr>
+    </tbody>
+</table>
+
+<h4>{{ _('Test mail')}} </h4>
+<form id="test_mail_form" action="" method="POST">
+    {{ form.hidden_tag() }}
+    {{ render_field_with_errors(form.recipient) }}
+    {{ render_field(form.submit) }}
+</form>
+
+<p>
+    <button id="submit_async" type="button" class="btn btn-outline-primary">{{ _('Send test mail asynchronously') }}</button>
+    <div class="col-md">
+        <div id="result_container">
+        </div>
+        <div class="spinner-border m-3" role="status" id="spinner" style="display: none;">
+            <span class="sr-only">Loading&hellip;</span>
+        </div>
+        <div class="alert alert-danger m-3" role="alert" id="error_alert" style="display: none;"></div>
+    </div>
+</p>
+
+
+
+{% endblock %}
\ No newline at end of file
diff --git a/project/templates/admin/settings.html b/project/templates/admin/settings.html
index f06f06b..00887e4 100644
--- a/project/templates/admin/settings.html
+++ b/project/templates/admin/settings.html
@@ -5,7 +5,12 @@
 {%- endblock -%}
 {% block content %}
 
-<h1>{{ _('Settings') }}</h1>
+<nav aria-label="breadcrumb">
+    <ol class="breadcrumb">
+        <li class="breadcrumb-item"><a href="{{ url_for('admin') }}">{{ _('Admin') }}</a></li>
+        <li class="breadcrumb-item active" aria-current="page">{{ _('Settings') }}</li>
+    </ol>
+</nav>
 
 <form action="" method="POST">
     {{ form.hidden_tag() }}
diff --git a/project/templates/email/test_email.html b/project/templates/email/test_email.html
new file mode 100644
index 0000000..e8a6850
--- /dev/null
+++ b/project/templates/email/test_email.html
@@ -0,0 +1,6 @@
+{% extends "email/layout.html" %}
+{% from "_macros.html" import render_email_button %}
+{% block content %}
+<p>{{ _('This is a test mail') }}</p>
+{{ render_email_button(url_for('home', _external=True), _('Click here to open the site')) }}
+{% endblock %}
\ No newline at end of file
diff --git a/project/templates/email/test_email.txt b/project/templates/email/test_email.txt
new file mode 100644
index 0000000..8383563
--- /dev/null
+++ b/project/templates/email/test_email.txt
@@ -0,0 +1,3 @@
+{{ _('This is a test mail') }}
+{{ _('Click the link below to open the site') }}
+{{ url_for('home', _external=True) }}
diff --git a/project/translations/de/LC_MESSAGES/messages.mo b/project/translations/de/LC_MESSAGES/messages.mo
index 790319e..53cabf6 100644
Binary files a/project/translations/de/LC_MESSAGES/messages.mo and b/project/translations/de/LC_MESSAGES/messages.mo differ
diff --git a/project/translations/de/LC_MESSAGES/messages.po b/project/translations/de/LC_MESSAGES/messages.po
index 298f3e4..045c90c 100644
--- a/project/translations/de/LC_MESSAGES/messages.po
+++ b/project/translations/de/LC_MESSAGES/messages.po
@@ -7,7 +7,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PROJECT VERSION\n"
 "Report-Msgid-Bugs-To: EMAIL@ADDRESS\n"
-"POT-Creation-Date: 2023-03-16 19:11+0100\n"
+"POT-Creation-Date: 2023-03-24 21:24+0100\n"
 "PO-Revision-Date: 2020-06-07 18:51+0200\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language: de\n"
@@ -199,51 +199,51 @@ msgstr "message"
 msgid "You have received an invitation"
 msgstr "Du hast eine Einladung erhalten"
 
-#: project/forms/admin.py:10 project/templates/layout.html:294
-#: project/views/root.py:57
+#: project/forms/admin.py:11 project/templates/layout.html:294
+#: project/views/root.py:53
 msgid "Terms of service"
 msgstr "Nutzungsbedingungen"
 
-#: project/forms/admin.py:11 project/templates/layout.html:298
-#: project/views/root.py:65
+#: project/forms/admin.py:12 project/templates/layout.html:298
+#: project/views/root.py:61
 msgid "Legal notice"
 msgstr "Impressum"
 
-#: project/forms/admin.py:12 project/templates/_macros.html:1395
+#: project/forms/admin.py:13 project/templates/_macros.html:1395
 #: project/templates/layout.html:302
 #: project/templates/widget/event_suggestion/create.html:204
-#: project/views/admin_unit.py:73 project/views/root.py:73
+#: project/views/admin_unit.py:73 project/views/root.py:69
 msgid "Contact"
 msgstr "Kontakt"
 
-#: project/forms/admin.py:13 project/templates/layout.html:306
-#: project/views/root.py:81
+#: project/forms/admin.py:14 project/templates/layout.html:306
+#: project/views/root.py:77
 msgid "Privacy"
 msgstr "Datenschutz"
 
-#: project/forms/admin.py:14
+#: project/forms/admin.py:15
 msgid "Start page"
 msgstr "Startseite"
 
-#: project/forms/admin.py:16 project/forms/oauth2_client.py:24
+#: project/forms/admin.py:17 project/forms/oauth2_client.py:24
 msgid "Save"
 msgstr "Speichern"
 
-#: project/forms/admin.py:20 project/forms/admin_unit_member.py:12
+#: project/forms/admin.py:21 project/forms/admin_unit_member.py:12
 #: project/forms/admin_unit_member.py:32
 msgid "Roles"
 msgstr "Rollen"
 
-#: project/forms/admin.py:21 project/templates/admin/update_user.html:4
+#: project/forms/admin.py:22 project/templates/admin/update_user.html:4
 #: project/templates/admin/update_user.html:8
 msgid "Update user"
 msgstr "Nutzer aktualisieren"
 
-#: project/forms/admin.py:26
+#: project/forms/admin.py:27
 msgid "Incoming reference requests allowed"
 msgstr "Eingehende Empfehlungsanfragen erlauben"
 
-#: project/forms/admin.py:27
+#: project/forms/admin.py:28
 msgid ""
 "If set, other organizations can ask this organization to reference their "
 "event."
@@ -251,49 +251,57 @@ msgstr ""
 "Wenn gesetzt, können andere Organisationen diese Organisation bitten, "
 "deren Veranstaltungen zu empfehlen."
 
-#: project/forms/admin.py:33
+#: project/forms/admin.py:34
 msgid "Suggestions enabled"
 msgstr "Vorschläge aktiv"
 
-#: project/forms/admin.py:34
+#: project/forms/admin.py:35
 msgid "If set, the organization can work with suggestions."
 msgstr "Wenn gesetzt, kann die Organisation mit Vorschlägen arbeiten."
 
-#: project/forms/admin.py:38
+#: project/forms/admin.py:39
 msgid "Create other organizations"
 msgstr "Andere Organisationen erstellen"
 
-#: project/forms/admin.py:39
+#: project/forms/admin.py:40
 msgid "If set, members of the organization can create other organizations."
 msgstr ""
 "Wenn gesetzt, können Mitglieder der Organisation andere Organisationen "
 "erstellen."
 
-#: project/forms/admin.py:45
+#: project/forms/admin.py:46
 msgid "Invite other organizations"
 msgstr "Andere Organisationen einladen"
 
-#: project/forms/admin.py:46
+#: project/forms/admin.py:47
 msgid "If set, members of the organization can invite other organizations."
 msgstr ""
 "Wenn gesetzt, können Mitglieder der Organisation andere Organisationen "
 "einladen."
 
-#: project/forms/admin.py:52
+#: project/forms/admin.py:53
 msgid "Verify other organizations"
 msgstr "Andere Organisationen verifizieren"
 
-#: project/forms/admin.py:53
+#: project/forms/admin.py:54
 msgid "If set, members of the organization can verify other organizations."
 msgstr ""
 "Wenn gesetzt, können Mitglieder der Organisation andere Organisationen "
 "verifizieren."
 
-#: project/forms/admin.py:58 project/templates/admin/update_admin_unit.html:4
+#: project/forms/admin.py:59 project/templates/admin/update_admin_unit.html:4
 #: project/templates/admin/update_admin_unit.html:8
 msgid "Update organization"
 msgstr "Organisation aktualisieren"
 
+#: project/forms/admin.py:63
+msgid "Recipient"
+msgstr "Empfänger"
+
+#: project/forms/admin.py:65
+msgid "Send test mail synchronously"
+msgstr "Test-Mail synchron senden"
+
 #: project/forms/admin_unit.py:15 project/forms/event_place.py:12
 #: project/forms/organizer.py:12
 msgid "Street"
@@ -360,7 +368,8 @@ msgstr "Link URL"
 #: project/forms/admin_unit_member.py:23 project/forms/admin_unit_member.py:28
 #: project/forms/event.py:107 project/forms/event_suggestion.py:38
 #: project/forms/organizer.py:27 project/templates/_macros.html:235
-#: project/templates/_macros.html:1491 project/templates/admin/users.html:19
+#: project/templates/_macros.html:1491 project/templates/admin/admin.html:27
+#: project/templates/admin/users.html:19
 msgid "Email"
 msgstr "Email"
 
@@ -1415,15 +1424,10 @@ msgstr "Veranstalter eingeben"
 msgid "Enter list name"
 msgstr "Listenname eingeben"
 
-#: project/templates/home.html:27
+#: project/templates/home.html:24
 msgid "Manage"
 msgstr "Verwaltung"
 
-#: project/templates/home.html:29 project/templates/security/login_user.html:38
-#: project/views/widget.py:159
-msgid "Register for free"
-msgstr "Kostenlos registrieren"
-
 #: project/templates/layout.html:152 project/templates/layout.html:200
 #: project/templates/manage/events.html:6
 #: project/templates/manage/events.html:42
@@ -1459,6 +1463,8 @@ msgstr "Profil"
 
 #: project/templates/admin/admin.html:3 project/templates/admin/admin.html:9
 #: project/templates/admin/admin_units.html:10
+#: project/templates/admin/email.html:65
+#: project/templates/admin/settings.html:10
 #: project/templates/admin/users.html:10 project/templates/layout.html:171
 msgid "Admin"
 msgstr "Administration"
@@ -1545,9 +1551,10 @@ msgstr "Beziehungen"
 msgid "Organization invitations"
 msgstr "Organisationseinladungen"
 
-#: project/templates/admin/admin.html:15
+#: project/templates/admin/admin.html:15 project/templates/admin/email.html:4
+#: project/templates/admin/email.html:66
 #: project/templates/admin/settings.html:4
-#: project/templates/admin/settings.html:8
+#: project/templates/admin/settings.html:11
 #: project/templates/admin_unit/update.html:6
 #: project/templates/admin_unit/update.html:23
 #: project/templates/layout.html:253 project/templates/manage/widgets.html:11
@@ -1603,6 +1610,18 @@ msgstr "Benutzer"
 msgid "Edit"
 msgstr "Bearbeiten"
 
+#: project/templates/admin/email.html:47 project/views/admin.py:119
+msgid "Mail sent successfully"
+msgstr "Mail erfolgreich gesendet"
+
+#: project/templates/admin/email.html:103
+msgid "Test mail"
+msgstr "Test-Mail"
+
+#: project/templates/admin/email.html:111
+msgid "Send test mail asynchronously"
+msgstr "Test-Mail asynchron senden"
+
 #: project/templates/admin_unit/create.html:58
 #: project/templates/admin_unit/update.html:59
 #: project/templates/event/create.html:347
@@ -1717,6 +1736,14 @@ msgstr "Klicke hier, um den Vorschlag zu prüfen"
 msgid "The review status of your event has been updated."
 msgstr "Der Prüfungsstatus deiner Veranstaltung wurde aktualisiert"
 
+#: project/templates/email/test_email.html:4
+msgid "This is a test mail"
+msgstr "Das ist eine Test-Mail"
+
+#: project/templates/email/test_email.html:5
+msgid "Click here to open the site"
+msgstr "Klicke hier, um die Seite zu öffnen"
+
 #: project/templates/event/actions.html:5
 #: project/templates/event/actions.html:22
 msgid "Actions for event"
@@ -2045,6 +2072,10 @@ msgstr "Angemeldet bleiben"
 msgid "You do not have an account yet? Not a problem!"
 msgstr "Du hast noch keinen Account? Kein Problem!"
 
+#: project/templates/security/login_user.html:38 project/views/widget.py:159
+msgid "Register for free"
+msgstr "Kostenlos registrieren"
+
 #: project/templates/widget/event_date/list.html:5
 msgid "Widget"
 msgstr "Widget"
@@ -2065,15 +2096,20 @@ msgstr "Optionale Details"
 msgid "Preview"
 msgstr "Vorschau"
 
-#: project/views/admin.py:44
+#: project/views/admin.py:55
 msgid "Organization successfully updated"
 msgstr "Organisation erfolgreich aktualisiert"
 
-#: project/views/admin.py:68 project/views/manage.py:361
+#: project/views/admin.py:79 project/views/manage.py:361
 msgid "Settings successfully updated"
 msgstr "Einstellungen erfolgreich aktualisiert"
 
-#: project/views/admin.py:103
+#: project/views/admin.py:108
+#, python-format
+msgid "Test mail from %(site_name)s"
+msgstr "Test-Mail from %(site_name)s"
+
+#: project/views/admin.py:152
 msgid "User successfully updated"
 msgstr "Nutzer erfolgreich aktualisiert"
 
diff --git a/project/translations/en/LC_MESSAGES/messages.mo b/project/translations/en/LC_MESSAGES/messages.mo
index 2657414..f1fcd1d 100644
Binary files a/project/translations/en/LC_MESSAGES/messages.mo and b/project/translations/en/LC_MESSAGES/messages.mo differ
diff --git a/project/translations/en/LC_MESSAGES/messages.po b/project/translations/en/LC_MESSAGES/messages.po
index b62c284..e38fe4b 100644
--- a/project/translations/en/LC_MESSAGES/messages.po
+++ b/project/translations/en/LC_MESSAGES/messages.po
@@ -7,7 +7,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PROJECT VERSION\n"
 "Report-Msgid-Bugs-To: EMAIL@ADDRESS\n"
-"POT-Creation-Date: 2023-03-16 19:11+0100\n"
+"POT-Creation-Date: 2023-03-24 21:24+0100\n"
 "PO-Revision-Date: 2021-04-30 15:04+0200\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language: en\n"
@@ -199,93 +199,101 @@ msgstr ""
 msgid "You have received an invitation"
 msgstr ""
 
-#: project/forms/admin.py:10 project/templates/layout.html:294
-#: project/views/root.py:57
+#: project/forms/admin.py:11 project/templates/layout.html:294
+#: project/views/root.py:53
 msgid "Terms of service"
 msgstr ""
 
-#: project/forms/admin.py:11 project/templates/layout.html:298
-#: project/views/root.py:65
+#: project/forms/admin.py:12 project/templates/layout.html:298
+#: project/views/root.py:61
 msgid "Legal notice"
 msgstr ""
 
-#: project/forms/admin.py:12 project/templates/_macros.html:1395
+#: project/forms/admin.py:13 project/templates/_macros.html:1395
 #: project/templates/layout.html:302
 #: project/templates/widget/event_suggestion/create.html:204
-#: project/views/admin_unit.py:73 project/views/root.py:73
+#: project/views/admin_unit.py:73 project/views/root.py:69
 msgid "Contact"
 msgstr ""
 
-#: project/forms/admin.py:13 project/templates/layout.html:306
-#: project/views/root.py:81
+#: project/forms/admin.py:14 project/templates/layout.html:306
+#: project/views/root.py:77
 msgid "Privacy"
 msgstr ""
 
-#: project/forms/admin.py:14
+#: project/forms/admin.py:15
 msgid "Start page"
 msgstr ""
 
-#: project/forms/admin.py:16 project/forms/oauth2_client.py:24
+#: project/forms/admin.py:17 project/forms/oauth2_client.py:24
 msgid "Save"
 msgstr ""
 
-#: project/forms/admin.py:20 project/forms/admin_unit_member.py:12
+#: project/forms/admin.py:21 project/forms/admin_unit_member.py:12
 #: project/forms/admin_unit_member.py:32
 msgid "Roles"
 msgstr ""
 
-#: project/forms/admin.py:21 project/templates/admin/update_user.html:4
+#: project/forms/admin.py:22 project/templates/admin/update_user.html:4
 #: project/templates/admin/update_user.html:8
 msgid "Update user"
 msgstr ""
 
-#: project/forms/admin.py:26
+#: project/forms/admin.py:27
 msgid "Incoming reference requests allowed"
 msgstr ""
 
-#: project/forms/admin.py:27
+#: project/forms/admin.py:28
 msgid ""
 "If set, other organizations can ask this organization to reference their "
 "event."
 msgstr ""
 
-#: project/forms/admin.py:33
+#: project/forms/admin.py:34
 msgid "Suggestions enabled"
 msgstr ""
 
-#: project/forms/admin.py:34
+#: project/forms/admin.py:35
 msgid "If set, the organization can work with suggestions."
 msgstr ""
 
-#: project/forms/admin.py:38
+#: project/forms/admin.py:39
 msgid "Create other organizations"
 msgstr ""
 
-#: project/forms/admin.py:39
+#: project/forms/admin.py:40
 msgid "If set, members of the organization can create other organizations."
 msgstr ""
 
-#: project/forms/admin.py:45
+#: project/forms/admin.py:46
 msgid "Invite other organizations"
 msgstr ""
 
-#: project/forms/admin.py:46
+#: project/forms/admin.py:47
 msgid "If set, members of the organization can invite other organizations."
 msgstr ""
 
-#: project/forms/admin.py:52
+#: project/forms/admin.py:53
 msgid "Verify other organizations"
 msgstr ""
 
-#: project/forms/admin.py:53
+#: project/forms/admin.py:54
 msgid "If set, members of the organization can verify other organizations."
 msgstr ""
 
-#: project/forms/admin.py:58 project/templates/admin/update_admin_unit.html:4
+#: project/forms/admin.py:59 project/templates/admin/update_admin_unit.html:4
 #: project/templates/admin/update_admin_unit.html:8
 msgid "Update organization"
 msgstr ""
 
+#: project/forms/admin.py:63
+msgid "Recipient"
+msgstr ""
+
+#: project/forms/admin.py:65
+msgid "Send test mail synchronously"
+msgstr ""
+
 #: project/forms/admin_unit.py:15 project/forms/event_place.py:12
 #: project/forms/organizer.py:12
 msgid "Street"
@@ -349,7 +357,8 @@ msgstr ""
 #: project/forms/admin_unit_member.py:23 project/forms/admin_unit_member.py:28
 #: project/forms/event.py:107 project/forms/event_suggestion.py:38
 #: project/forms/organizer.py:27 project/templates/_macros.html:235
-#: project/templates/_macros.html:1491 project/templates/admin/users.html:19
+#: project/templates/_macros.html:1491 project/templates/admin/admin.html:27
+#: project/templates/admin/users.html:19
 msgid "Email"
 msgstr ""
 
@@ -1366,15 +1375,10 @@ msgstr ""
 msgid "Enter list name"
 msgstr ""
 
-#: project/templates/home.html:27
+#: project/templates/home.html:24
 msgid "Manage"
 msgstr ""
 
-#: project/templates/home.html:29 project/templates/security/login_user.html:38
-#: project/views/widget.py:159
-msgid "Register for free"
-msgstr ""
-
 #: project/templates/layout.html:152 project/templates/layout.html:200
 #: project/templates/manage/events.html:6
 #: project/templates/manage/events.html:42
@@ -1410,6 +1414,8 @@ msgstr ""
 
 #: project/templates/admin/admin.html:3 project/templates/admin/admin.html:9
 #: project/templates/admin/admin_units.html:10
+#: project/templates/admin/email.html:65
+#: project/templates/admin/settings.html:10
 #: project/templates/admin/users.html:10 project/templates/layout.html:171
 msgid "Admin"
 msgstr ""
@@ -1496,9 +1502,10 @@ msgstr ""
 msgid "Organization invitations"
 msgstr ""
 
-#: project/templates/admin/admin.html:15
+#: project/templates/admin/admin.html:15 project/templates/admin/email.html:4
+#: project/templates/admin/email.html:66
 #: project/templates/admin/settings.html:4
-#: project/templates/admin/settings.html:8
+#: project/templates/admin/settings.html:11
 #: project/templates/admin_unit/update.html:6
 #: project/templates/admin_unit/update.html:23
 #: project/templates/layout.html:253 project/templates/manage/widgets.html:11
@@ -1554,6 +1561,18 @@ msgstr ""
 msgid "Edit"
 msgstr ""
 
+#: project/templates/admin/email.html:47 project/views/admin.py:119
+msgid "Mail sent successfully"
+msgstr ""
+
+#: project/templates/admin/email.html:103
+msgid "Test mail"
+msgstr ""
+
+#: project/templates/admin/email.html:111
+msgid "Send test mail asynchronously"
+msgstr ""
+
 #: project/templates/admin_unit/create.html:58
 #: project/templates/admin_unit/update.html:59
 #: project/templates/event/create.html:347
@@ -1666,6 +1685,14 @@ msgstr ""
 msgid "The review status of your event has been updated."
 msgstr ""
 
+#: project/templates/email/test_email.html:4
+msgid "This is a test mail"
+msgstr ""
+
+#: project/templates/email/test_email.html:5
+msgid "Click here to open the site"
+msgstr ""
+
 #: project/templates/event/actions.html:5
 #: project/templates/event/actions.html:22
 msgid "Actions for event"
@@ -1985,6 +2012,10 @@ msgstr ""
 msgid "You do not have an account yet? Not a problem!"
 msgstr ""
 
+#: project/templates/security/login_user.html:38 project/views/widget.py:159
+msgid "Register for free"
+msgstr ""
+
 #: project/templates/widget/event_date/list.html:5
 msgid "Widget"
 msgstr ""
@@ -2005,15 +2036,20 @@ msgstr ""
 msgid "Preview"
 msgstr ""
 
-#: project/views/admin.py:44
+#: project/views/admin.py:55
 msgid "Organization successfully updated"
 msgstr ""
 
-#: project/views/admin.py:68 project/views/manage.py:361
+#: project/views/admin.py:79 project/views/manage.py:361
 msgid "Settings successfully updated"
 msgstr ""
 
-#: project/views/admin.py:103
+#: project/views/admin.py:108
+#, python-format
+msgid "Test mail from %(site_name)s"
+msgstr ""
+
+#: project/views/admin.py:152
 msgid "User successfully updated"
 msgstr ""
 
diff --git a/project/views/admin.py b/project/views/admin.py
index 5482d0f..b31ba16 100644
--- a/project/views/admin.py
+++ b/project/views/admin.py
@@ -1,15 +1,26 @@
-from flask import flash, redirect, render_template, url_for
+from flask import flash, redirect, render_template, request, url_for
 from flask_babelex import gettext
 from flask_security import roles_required
 from sqlalchemy.exc import SQLAlchemyError
 from sqlalchemy.sql import func
 
-from project import app, db
-from project.forms.admin import AdminSettingsForm, UpdateAdminUnitForm, UpdateUserForm
+from project import app, celery, db
+from project.base_tasks import send_mail_task
+from project.forms.admin import (
+    AdminSettingsForm,
+    AdminTestEmailForm,
+    UpdateAdminUnitForm,
+    UpdateUserForm,
+)
 from project.models import AdminUnit, Role, User
 from project.services.admin import upsert_settings
 from project.services.user import set_roles_for_user
-from project.views.utils import flash_errors, get_pagination_urls, handleSqlError
+from project.views.utils import (
+    flash_errors,
+    get_pagination_urls,
+    handleSqlError,
+    send_mail,
+)
 
 
 @app.route("/admin")
@@ -76,6 +87,44 @@ def admin_settings():
     return render_template("admin/settings.html", form=form)
 
 
+@app.route("/admin/email", methods=["GET", "POST"])
+@roles_required("admin")
+def admin_email():
+    form = AdminTestEmailForm()
+
+    if "poll" in request.args:  # pragma: no cover
+        try:
+            result = celery.AsyncResult(request.args["poll"])
+            ready = result.ready()
+            return {
+                "ready": ready,
+                "successful": result.successful() if ready else None,
+                "value": result.get() if ready else result.result,
+            }
+        except Exception as e:
+            return {"ready": True, "successful": False, "error": str(e)}
+
+    if form.validate_on_submit():
+        subject = gettext(
+            "Test mail from %(site_name)s",
+            site_name=app.config["SITE_NAME"],
+        )
+
+        if "async" in request.args:  # pragma: no cover
+            result = send_mail_task.delay(form.recipient.data, subject, "test_email")
+            return {"result_id": result.id}
+
+        try:
+            send_mail(form.recipient.data, subject, "test_email")
+            flash(gettext("Mail sent successfully"), "success")
+        except Exception as e:  # pragma: no cover
+            flash(str(e), "danger")
+    else:  # pragma: no cover
+        flash_errors(form)
+
+    return render_template("admin/email.html", form=form)
+
+
 @app.route("/admin/users")
 @roles_required("admin")
 def admin_users():
diff --git a/project/views/utils.py b/project/views/utils.py
index a68a33d..746a515 100644
--- a/project/views/utils.py
+++ b/project/views/utils.py
@@ -27,7 +27,7 @@ def get_current_admin_unit(fallback=True):
     if admin_unit:
         return admin_unit
 
-    if current_user.is_authenticated:
+    if current_user and current_user.is_authenticated:
         admin_unit = get_current_admin_unit_from_cookies()
 
         if not admin_unit and fallback:
@@ -44,7 +44,7 @@ def get_current_admin_unit(fallback=True):
 
 def get_current_admin_unit_from_cookies():
     try:
-        if "manage_admin_unit_id" in request.cookies:
+        if request and request.cookies and "manage_admin_unit_id" in request.cookies:
             encoded = request.cookies.get("manage_admin_unit_id")
             manage_admin_unit_id = int(decode_cookie(encoded))
             return get_admin_unit_for_manage(manage_admin_unit_id)
diff --git a/requirements.txt b/requirements.txt
index c21be42..4fdf330 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -17,7 +17,6 @@ black==23.1.0
 blinker==1.4
 cached-property==1.5.2
 celery==5.2.7
-celery-singleton==0.3.1
 certifi==2020.12.5
 cffi==1.14.4
 cfgv==3.2.0
@@ -121,7 +120,7 @@ TatSu==4.4.0
 toml==0.10.2
 tomli==2.0.1
 typed-ast==1.5.4
-typing_extensions==4.5.0
+typing-extensions==4.5.0
 urllib3==1.26.5
 URLObject==2.4.3
 validators==0.18.2
diff --git a/tests/views/test_admin.py b/tests/views/test_admin.py
index cbcdf4e..058971d 100644
--- a/tests/views/test_admin.py
+++ b/tests/views/test_admin.py
@@ -60,6 +60,25 @@ def test_admin_settings(client, seeder, utils, app, mocker, db_error):
         assert settings.privacy == "Mein Datenschutz"
 
 
+def test_admin_email(client, seeder, utils, app, mocker):
+    user_id, admin_unit_id = seeder.setup_base(True)
+
+    url = utils.get_url("admin_email")
+    response = utils.get_ok(url)
+
+    mail_mock = utils.mock_send_mails(mocker)
+    response = utils.post_form(
+        url,
+        response,
+        {
+            "recipient": "test@test.de",
+        },
+    )
+
+    utils.assert_response_ok(response)
+    utils.assert_send_mail_called(mail_mock, "test@test.de")
+
+
 def test_admin_users(client, seeder, utils, app):
     seeder.create_user(admin=True)
     user = utils.login()
diff --git a/tests/views/test_app.py b/tests/views/test_app.py
index 888f824..0f5fc9e 100644
--- a/tests/views/test_app.py
+++ b/tests/views/test_app.py
@@ -1,3 +1,3 @@
 def test_index(client):
     response = client.get("/")
-    assert b"eventcally" in response.data
+    assert b"EventCally" in response.data