diff --git a/app/assets/javascripts/app/controllers/_settings/area_item.coffee b/app/assets/javascripts/app/controllers/_settings/area_item.coffee
index c7db71eb3..877caeee0 100644
--- a/app/assets/javascripts/app/controllers/_settings/area_item.coffee
+++ b/app/assets/javascripts/app/controllers/_settings/area_item.coffee
@@ -32,7 +32,7 @@ class App.SettingsAreaItem extends App.Controller
     )
 
     new App.ControllerForm(
-      el: @el.find('.form-item'),
+      el: @el.find('.form-item')
       model: { configure_attributes: @configure_attributes, className: '' }
       autofocus: false
     )
diff --git a/app/assets/javascripts/app/controllers/_settings/area_item_default_locale.coffee b/app/assets/javascripts/app/controllers/_settings/area_item_default_locale.coffee
new file mode 100644
index 000000000..5d22c5a59
--- /dev/null
+++ b/app/assets/javascripts/app/controllers/_settings/area_item_default_locale.coffee
@@ -0,0 +1,21 @@
+class App.SettingsAreaItemDefaultLocale extends App.SettingsAreaItem
+
+  render: =>
+
+    options = {}
+    locales = App.Locale.all()
+    for locale in locales
+      options[locale.locale] = locale.name
+    configure_attributes = [
+      { name: 'locale_default', display: '', tag: 'searchable_select', null: false, class: 'input', options: options, default: @setting.state_current.value },
+    ]
+
+    @html App.view(@template)(
+      setting: @setting
+    )
+
+    new App.ControllerForm(
+      el: @el.find('.form-item')
+      model: { configure_attributes: configure_attributes, className: '' }
+      autofocus: false
+    )
diff --git a/app/assets/javascripts/app/controllers/widget/default_locale.coffee b/app/assets/javascripts/app/controllers/widget/default_locale.coffee
new file mode 100644
index 000000000..db4437c30
--- /dev/null
+++ b/app/assets/javascripts/app/controllers/widget/default_locale.coffee
@@ -0,0 +1,23 @@
+class DefaultLocale extends App.Controller
+  constructor: ->
+    super
+
+    check = =>
+
+      preferences = App.Session.get('preferences')
+      return if !preferences
+      return if !_.isEmpty(preferences.locale)
+      locale = App.i18n.get()
+      @ajax(
+        id:          "i18n-set-user-#{locale}"
+        type:        'PUT'
+        url:         "#{App.Config.get('api_path')}/users/preferences"
+        data:        JSON.stringify(locale: locale)
+        processData: true
+      )
+
+    App.Event.bind('auth:login', (session) =>
+      @delay(check, 3500, 'default_locale')
+    )
+
+App.Config.set('default_locale', DefaultLocale, 'Widgets')
diff --git a/app/assets/javascripts/app/controllers/widget/switch_back_to_user.coffee b/app/assets/javascripts/app/controllers/widget/switch_back_to_user.coffee
index 9f5e3c526..612d9cbe4 100644
--- a/app/assets/javascripts/app/controllers/widget/switch_back_to_user.coffee
+++ b/app/assets/javascripts/app/controllers/widget/switch_back_to_user.coffee
@@ -47,4 +47,4 @@ class Widget extends App.ControllerWidgetOnDemand
       800
     )
 
-App.Config.set( 'switch_back_to_user', Widget, 'Widgets' )
+App.Config.set('switch_back_to_user', Widget, 'Widgets')
diff --git a/app/assets/javascripts/app/lib/app_post/auth.coffee b/app/assets/javascripts/app/lib/app_post/auth.coffee
index f46c8c6e3..7f95f2375 100644
--- a/app/assets/javascripts/app/lib/app_post/auth.coffee
+++ b/app/assets/javascripts/app/lib/app_post/auth.coffee
@@ -79,8 +79,7 @@ class App.Auth
       @_updateModelAttributes(data.models)
 
       # set locale
-      locale = window.navigator.userLanguage || window.navigator.language || 'en-us'
-      App.i18n.set(locale)
+      App.i18n.set(App.i18n.detectBrowserLocale())
 
       # rebuild navbar with new navbar items
       App.Event.trigger('auth')
@@ -120,7 +119,7 @@ class App.Auth
     if preferences && preferences.locale
       locale = preferences.locale
     if !locale
-      locale = window.navigator.userLanguage || window.navigator.language || 'en-us'
+      locale = App.i18n.detectBrowserLocale()
     App.i18n.set(locale)
 
     App.Event.trigger('auth:login', data.session)
diff --git a/app/assets/javascripts/app/lib/app_post/i18n.coffee b/app/assets/javascripts/app/lib/app_post/i18n.coffee
index 560562269..af8b5ef3d 100644
--- a/app/assets/javascripts/app/lib/app_post/i18n.coffee
+++ b/app/assets/javascripts/app/lib/app_post/i18n.coffee
@@ -80,6 +80,24 @@ class App.i18n
       _instance ?= new _i18nSingleton()
     _instance.mapTime
 
+  @detectBrowserLocale: ->
+    return 'en-us' if !window.navigator.userLanguage && !window.navigator.language
+
+    if window.navigator.languages
+      allLocales = App.Locale.all()
+      for browserLocale in window.navigator.languages
+        for localAllLocale in allLocales
+          if browserLocale is localAllLocale.locale
+            return localAllLocale.locale
+
+      for browserLocale in window.navigator.languages
+        browserLocale = browserLocale.substr(0, 2)
+        for localAllLocale in allLocales
+          if browserLocale is localAllLocale.alias
+            return localAllLocale.locale
+
+    window.navigator.userLanguage || window.navigator.language || 'en-us'
+
 class _i18nSingleton extends Spine.Module
   @include App.LogInclude
 
diff --git a/app/controllers/first_steps_controller.rb b/app/controllers/first_steps_controller.rb
index 096879693..0dd392be3 100644
--- a/app/controllers/first_steps_controller.rb
+++ b/app/controllers/first_steps_controller.rb
@@ -177,7 +177,7 @@ class FirstStepsController < ApplicationController
     original_user_id = UserInfo.current_user_id
     result = NotificationFactory::Mailer.template(
       template: 'test_ticket',
-      locale: agent.preferences[:locale] || 'en-us',
+      locale: agent.preferences[:locale] || Setting.get('locale_default') || 'en-us',
       objects:  {
         agent: agent,
         customer: customer,
diff --git a/app/models/locale.rb b/app/models/locale.rb
index 4ce319646..fa597f189 100644
--- a/app/models/locale.rb
+++ b/app/models/locale.rb
@@ -24,7 +24,7 @@ returns
 
     # read used locales based on env, e. g. export Z_LOCALES='en-us:de-de'
     if ENV['Z_LOCALES']
-      locales = Locale.where(active: true, locale: ENV['Z_LOCALES'].split(':') )
+      locales = Locale.where(active: true, locale: ENV['Z_LOCALES'].split(':'))
     end
     locales
   end
diff --git a/app/models/text_module.rb b/app/models/text_module.rb
index b01d3a037..1cec59992 100644
--- a/app/models/text_module.rb
+++ b/app/models/text_module.rb
@@ -18,7 +18,7 @@ load text modules from online
 =end
 
   def self.load(locale, overwrite_existing_item = false)
-    raise 'Got no locale' if locale.empty?
+    raise 'Got no locale' if locale.blank?
     locale = locale.split(',').first.downcase # in case of accept_language header is given
     url = "https://i18n.zammad.com/api/v1/text_modules/#{locale}"
 
@@ -67,7 +67,7 @@ push text_modules to online
       text_modules_to_push.push text_module
     end
 
-    return true if text_modules_to_push.empty?
+    return true if text_modules_to_push.blank?
 
     url = 'https://i18n.zammad.com/api/v1/text_modules/thanks_for_your_support'
 
diff --git a/app/models/transaction/clearbit_enrichment.rb b/app/models/transaction/clearbit_enrichment.rb
index b9c186e9b..e38f9a052 100644
--- a/app/models/transaction/clearbit_enrichment.rb
+++ b/app/models/transaction/clearbit_enrichment.rb
@@ -31,7 +31,7 @@ class Transaction::ClearbitEnrichment
 
     config = Setting.get('clearbit_config')
     return if !config
-    return if config['api_key'].empty?
+    return if config['api_key'].blank?
 
     user = User.lookup(id: @item[:object_id])
     return if !user
diff --git a/app/models/transaction/notification.rb b/app/models/transaction/notification.rb
index 398426e0b..8c5a74539 100644
--- a/app/models/transaction/notification.rb
+++ b/app/models/transaction/notification.rb
@@ -231,7 +231,7 @@ class Transaction::Notification
   def human_changes(user, record)
 
     return {} if !@item[:changes]
-    locale = user.preferences[:locale] || 'en-us'
+    locale = user.preferences[:locale] || Setting.get('locale_default') || 'en-us'
 
     # only show allowed attributes
     attribute_list = ObjectManager::Attribute.by_object_as_hash('Ticket', user)
diff --git a/app/models/transaction/slack.rb b/app/models/transaction/slack.rb
index 124685618..aac7d393a 100644
--- a/app/models/transaction/slack.rb
+++ b/app/models/transaction/slack.rb
@@ -197,7 +197,7 @@ class Transaction::Slack
 
     return {} if !@item[:changes]
     user = User.find(1)
-    locale = user.preferences[:locale] || 'en-us'
+    locale = user.preferences[:locale] || Setting.get('locale_default') || 'en-us'
 
     # only show allowed attributes
     attribute_list = ObjectManager::Attribute.by_object_as_hash('Ticket', user)
diff --git a/app/models/translation.rb b/app/models/translation.rb
index 5a406a21a..dbb013345 100644
--- a/app/models/translation.rb
+++ b/app/models/translation.rb
@@ -65,7 +65,7 @@ push translations to online
       end
     end
 
-    return true if translations_to_push.empty?
+    return true if translations_to_push.blank?
 
     url = 'https://i18n.zammad.com/api/v1/translations/thanks_for_your_support'
 
@@ -108,7 +108,7 @@ reset translations to origin
     # only push changed translations
     translations = Translation.where(locale: locale)
     translations.each do |translation|
-      if !translation.target_initial || translation.target_initial.empty?
+      if translation.target_initial.blank?
         translation.destroy
       elsif translation.target != translation.target_initial
         translation.target = translation.target_initial
diff --git a/db/migrate/20171115000001_setting_default_locale.rb b/db/migrate/20171115000001_setting_default_locale.rb
new file mode 100644
index 000000000..e91bbfa12
--- /dev/null
+++ b/db/migrate/20171115000001_setting_default_locale.rb
@@ -0,0 +1,28 @@
+class SettingDefaultLocale < ActiveRecord::Migration[5.1]
+  def up
+
+    # return if it's a new setup
+    return if !Setting.find_by(name: 'system_init_done')
+
+    Setting.create_if_not_exists(
+      title: 'Locale',
+      name: 'locale_default',
+      area: 'System::Base',
+      description: 'Defines the system default language.',
+      options: {
+        form: [
+          {
+            name: 'locale_default',
+          }
+        ],
+      },
+      state: 'en-us',
+      preferences: {
+        controller: 'SettingsAreaItemDefaultLocale',
+        permission: ['admin.system'],
+      },
+      frontend: true
+    )
+  end
+
+end
diff --git a/db/seeds/settings.rb b/db/seeds/settings.rb
index 12b351599..decad0c72 100644
--- a/db/seeds/settings.rb
+++ b/db/seeds/settings.rb
@@ -183,6 +183,25 @@ Setting.create_or_update(
   state: 'relative',
   frontend: true
 )
+Setting.create_if_not_exists(
+  title: 'Locale',
+  name: 'locale_default',
+  area: 'System::Base',
+  description: 'Defines the system default language.',
+  options: {
+    form: [
+      {
+        name: 'locale_default',
+      }
+    ],
+  },
+  state: 'en-us',
+  preferences: {
+    controller: 'SettingsAreaItemDefaultLocale',
+    permission: ['admin.system'],
+  },
+  frontend: true
+)
 options = {}
 (10..99).each do |item|
   options[item] = item
diff --git a/lib/calendar_subscriptions/tickets.rb b/lib/calendar_subscriptions/tickets.rb
index 631538042..571c2c698 100644
--- a/lib/calendar_subscriptions/tickets.rb
+++ b/lib/calendar_subscriptions/tickets.rb
@@ -11,7 +11,7 @@ class CalendarSubscriptions::Tickets
   def all
 
     events_data = []
-    return events_data if @preferences.empty?
+    return events_data if @preferences.blank?
 
     events_data += new_open
     events_data += pending
@@ -24,7 +24,7 @@ class CalendarSubscriptions::Tickets
 
     alarm = false
 
-    return alarm if @preferences.empty?
+    return alarm if @preferences.blank?
     return alarm if !@preferences[:alarm]
 
     @preferences[:alarm]
@@ -34,11 +34,11 @@ class CalendarSubscriptions::Tickets
 
     owner_ids = []
 
-    return owner_ids if @preferences.empty?
-    return owner_ids if !@preferences[ method ]
-    return owner_ids if @preferences[ method ].empty?
+    return owner_ids if @preferences.blank?
+    return owner_ids if !@preferences[method]
+    return owner_ids if @preferences[method].blank?
 
-    preferences = @preferences[ method ]
+    preferences = @preferences[method]
 
     if preferences[:own]
       owner_ids = [ @user.id ]
@@ -54,7 +54,7 @@ class CalendarSubscriptions::Tickets
 
     events_data = []
     owner_ids   = owner_ids(:new_open)
-    return events_data if owner_ids.empty?
+    return events_data if owner_ids.blank?
 
     condition = {
       'ticket.owner_id' => {
@@ -76,7 +76,7 @@ class CalendarSubscriptions::Tickets
       condition: condition,
     )
 
-    user_locale       = @user.preferences['locale'] || 'en'
+    user_locale       = @user.preferences['locale'] || Setting.get('locale_default') || 'en-us'
     translated_ticket = Translation.translate(user_locale, 'ticket')
 
     events_data = []
@@ -101,7 +101,7 @@ class CalendarSubscriptions::Tickets
 
     events_data = []
     owner_ids   = owner_ids(:pending)
-    return events_data if owner_ids.empty?
+    return events_data if owner_ids.blank?
 
     condition = {
       'ticket.owner_id' => {
@@ -126,7 +126,7 @@ class CalendarSubscriptions::Tickets
       condition: condition,
     )
 
-    user_locale       = @user.preferences['locale'] || 'en'
+    user_locale       = @user.preferences['locale'] || Setting.get('locale_default') || 'en-us'
     translated_ticket = Translation.translate(user_locale, 'ticket')
     customer          = Translation.translate(user_locale, 'customer')
 
@@ -165,7 +165,7 @@ class CalendarSubscriptions::Tickets
 
     events_data = []
     owner_ids   = owner_ids(:escalation)
-    return events_data if owner_ids.empty?
+    return events_data if owner_ids.blank?
 
     condition = {
       'ticket.owner_id' => {
@@ -183,7 +183,7 @@ class CalendarSubscriptions::Tickets
       condition: condition,
     )
 
-    user_locale                  = @user.preferences['locale'] || 'en'
+    user_locale                  = @user.preferences['locale'] || Setting.get('locale_default') || 'en-us'
     translated_ticket_escalation = Translation.translate(user_locale, 'ticket escalation')
     customer                     = Translation.translate(user_locale, 'customer')
 
diff --git a/lib/notification_factory.rb b/lib/notification_factory.rb
index 26de217e3..477a9994e 100644
--- a/lib/notification_factory.rb
+++ b/lib/notification_factory.rb
@@ -31,7 +31,7 @@ returns
 
     template_subject = nil
     template_body = ''
-    locale = data[:locale] || 'en'
+    locale = data[:locale] || Setting.get('locale_default') || 'en-us'
     template = data[:template]
     format = data[:format]
     type = data[:type]
diff --git a/lib/notification_factory/mailer.rb b/lib/notification_factory/mailer.rb
index 68dec4cf8..b949f044e 100644
--- a/lib/notification_factory/mailer.rb
+++ b/lib/notification_factory/mailer.rb
@@ -264,7 +264,7 @@ returns
     end
 
     template = NotificationFactory.template_read(
-      locale: data[:locale] || 'en',
+      locale: data[:locale] || Setting.get('locale_default') || 'en-us',
       template: data[:template],
       format: 'html',
       type: 'mailer',
diff --git a/lib/notification_factory/renderer.rb b/lib/notification_factory/renderer.rb
index 680200f5e..5e700c876 100644
--- a/lib/notification_factory/renderer.rb
+++ b/lib/notification_factory/renderer.rb
@@ -25,7 +25,7 @@ examples how to use
 
   def initialize(objects, locale, template, escape = true)
     @objects = objects
-    @locale = locale || 'en-us'
+    @locale = locale || Setting.get('locale_default') || 'en-us'
     @template = NotificationFactory::Template.new(template, escape)
     @escape = escape
   end
diff --git a/lib/notification_factory/slack.rb b/lib/notification_factory/slack.rb
index da8dc3b6c..87221565a 100644
--- a/lib/notification_factory/slack.rb
+++ b/lib/notification_factory/slack.rb
@@ -27,7 +27,7 @@ returns
     end
 
     template = NotificationFactory.template_read(
-      locale: data[:locale] || 'en',
+      locale: data[:locale] || Setting.get('locale_default') || 'en-us',
       template: data[:template],
       format: 'md',
       type: 'slack',
diff --git a/test/unit/notification_factory_mailer_template_test.rb b/test/unit/notification_factory_mailer_template_test.rb
index 7889b6057..2dc38a9e8 100644
--- a/test/unit/notification_factory_mailer_template_test.rb
+++ b/test/unit/notification_factory_mailer_template_test.rb
@@ -201,6 +201,66 @@ class NotificationFactoryMailerTemplateTest < ActiveSupport::TestCase
     assert_no_match('longname', result[:body])
     assert_match('Current User', result[:body])
 
+    Setting.set('locale_default', 'de-de')
+    result = NotificationFactory::Mailer.template(
+      template: 'ticket_update',
+      objects:  {
+        ticket: ticket,
+        article: article,
+        recipient: agent1,
+        current_user: agent_current_user,
+        changes: changes,
+      },
+    )
+    assert_match('Ticket aktualisiert', result[:subject])
+    assert_match('Notification&lt;b&gt;xxx&lt;/b&gt;', result[:body])
+    assert_match('wurde von', result[:body])
+    assert_match('<b>test123</b>', result[:body])
+    assert_match('Benachrichtigungseinstellungen Verwalten', result[:body])
+    assert_no_match('Your', result[:body])
+    assert_no_match('longname', result[:body])
+    assert_match('Current User', result[:body])
+
+    Setting.set('locale_default', 'not_existing')
+    result = NotificationFactory::Mailer.template(
+      template: 'ticket_update',
+      objects:  {
+        ticket: ticket,
+        article: article,
+        recipient: agent1,
+        current_user: agent_current_user,
+        changes: changes,
+      },
+    )
+    assert_match('Updated Ticket', result[:subject])
+    assert_match('Notification&lt;b&gt;xxx&lt;/b&gt;', result[:body])
+    assert_match('has been updated by', result[:body])
+    assert_match('<b>test123</b>', result[:body])
+    assert_match('Manage your notifications settings', result[:body])
+    assert_no_match('Dein', result[:body])
+    assert_no_match('longname', result[:body])
+    assert_match('Current User', result[:body])
+
+    Setting.set('locale_default', 'pt-br')
+    result = NotificationFactory::Mailer.template(
+      template: 'ticket_update',
+      objects:  {
+        ticket: ticket,
+        article: article,
+        recipient: agent1,
+        current_user: agent_current_user,
+        changes: changes,
+      },
+    )
+    assert_match('Chamado atualizado', result[:subject])
+    assert_match('Notification&lt;b&gt;xxx&lt;/b&gt;', result[:body])
+    assert_match('foi atualizado por', result[:body])
+    assert_match('<b>test123</b>', result[:body])
+    assert_match('Manage your notifications settings', result[:body])
+    assert_no_match('Dein', result[:body])
+    assert_no_match('longname', result[:body])
+    assert_match('Current User', result[:body])
+
   end
 
 end