Add warning on admin dashboard if production env is configured to send email through gmail

app/models/admin_dashboard_data.rb

@@ -32,6 +32,7 @@ class AdminDashboardData
       failing_emails_check,
       default_logo_check,
       contact_email_check,
+      send_email_with_gmail_check,
       title_check ].compact
   end
 
@@ -120,4 +121,8 @@ class AdminDashboardData
     I18n.t('dashboard.title_nag') if SiteSetting.title == SiteSetting.defaults[:title]
   end
 
+  def send_email_with_gmail_check
+    I18n.t('dashboard.gmail_for_email_warning') if Rails.env == 'production' and ActionMailer::Base.smtp_settings[:address] =~ /gmail\.com/
+  end
+
 end

config/locales/server.en.yml

@@ -373,9 +373,9 @@ en:
   dashboard:
     rails_env_warning: "Your server is running in %{env} mode."
     host_names_warning: "Your config/database.yml file is using the default localhost hostname. Update it to use your site's hostname."
-    gc_warning: 'Your server is using default ruby garbage collection parameters, which will not give you the best performance. Read this topic on performance tuning: <a href="http://meta.discourse.org/t/tuning-ruby-and-rails-for-discourse/4126">Tuning Ruby and Rails for Discourse</a>.'
-    clockwork_warning: 'Clockwork is not running. Ensure that a clockwork process is always running so that important jobs can be scheduled. <a href="https://github.com/tomykaira/clockwork">Learn about clockwork here</a>.'
-    sidekiq_warning: 'Sidekiq is not running. Many tasks, like sending emails, are executed asynchronously by sidekiq. Please ensure at least one sidekiq process is running. <a href="https://github.com/mperham/sidekiq">Learn about Sidekiq here</a>.'
+    gc_warning: 'Your server is using default ruby garbage collection parameters, which will not give you the best performance. Read this topic on performance tuning: <a href="http://meta.discourse.org/t/tuning-ruby-and-rails-for-discourse/4126" target="_blank">Tuning Ruby and Rails for Discourse</a>.'
+    clockwork_warning: 'Clockwork is not running. Ensure that a clockwork process is always running so that important jobs can be scheduled. <a href="https://github.com/tomykaira/clockwork" target="_blank">Learn about clockwork here</a>.'
+    sidekiq_warning: 'Sidekiq is not running. Many tasks, like sending emails, are executed asynchronously by sidekiq. Please ensure at least one sidekiq process is running. <a href="https://github.com/mperham/sidekiq" target="_blank">Learn about Sidekiq here</a>.'
     queue_size_warning: 'The number of queued jobs is %{queue_size}, which is high. This could indicate a problem with the Sidekiq process(es), or you may need to add more Sidekiq workers.'
     memory_warning: 'Your server is running with less than 1 GB of total memory. At least 1 GB of memory is recommended.'
     facebook_config_warning: 'The server is configured to allow signup and log in with Facebook (enable_facebook_logins), but the app id and app secret values are not set. Go to <a href="/admin/site_settings">the Site Settings</a> and update the settings. <a href="https://github.com/discourse/discourse/wiki/The-Discourse-Admin-Quick-Start-Guide#enable-facebook-logins" target="_blank">See this guide to learn more</a>.'
@@ -387,6 +387,7 @@ en:
     contact_email_missing: "You haven't provided a contact email for your site. Please update contact_email in the <a href='/admin/site_settings'>Site Settings</a>."
     contact_email_invalid: "The site contact email is invalid. Please update contact_email in the <a href='/admin/site_settings'>Site Settings</a>."
     title_nag: "The title Site Setting is still set to the default value. Please update it with your site's title in the <a href='/admin/site_settings'>Site Settings</a>."
+    gmail_for_email_warning: "Your site is configured to use Gmail to send email. <a href='http://support.google.com/a/bin/answer.py?hl=en&answer=166852' target='_blank'>Gmail limits how many emails you can send</a>. Consider using an email service provider to ensure email deliverability."
 
   content_types:
     education_new_reply:

spec/models/admin_dashboard_data_spec.rb

@@ -121,9 +121,32 @@ describe AdminDashboardData do
     end
   end
 
+  describe 'send_email_with_gmail_check' do
+    subject { AdminDashboardData.new.send_email_with_gmail_check }
+
+    it 'returns nil if gmail.com is not in the smtp_settings address' do
+      ActionMailer::Base.stubs(:smtp_settings).returns({address: 'mandrillapp.com'})
+      expect(subject).to be_nil
+    end
+
+    context 'gmail.com is in the smtp_settings address' do
+      before { ActionMailer::Base.stubs(:smtp_settings).returns({address: 'smtp.gmail.com'}) }
+
+      it 'returns nil in development env' do
+        Rails.stubs(:env).returns('development')
+        expect(subject).to be_nil
+      end
+
+      it 'returns a string when in production env' do
+        Rails.stubs(:env).returns('production')
+        expect(subject).to_not be_nil
+      end
+    end
+  end
+
   describe 'auth_config_checks' do
 
-    shared_examples_for 'problem detection for login providers' do
+    shared_examples 'problem detection for login providers' do
       context 'when disabled' do
         it 'returns nil' do
           SiteSetting.stubs(enable_setting).returns(false)
@@ -167,7 +190,7 @@ describe AdminDashboardData do
       let(:enable_setting) { :enable_facebook_logins }
       let(:key) { :facebook_app_id }
       let(:secret) { :facebook_app_secret }
-      it_should_behave_like 'problem detection for login providers'
+      include_examples 'problem detection for login providers'
     end
 
     describe 'twitter' do
@@ -175,7 +198,7 @@ describe AdminDashboardData do
       let(:enable_setting) { :enable_twitter_logins }
       let(:key) { :twitter_consumer_key }
       let(:secret) { :twitter_consumer_secret }
-      it_should_behave_like 'problem detection for login providers'
+      include_examples 'problem detection for login providers'
     end
 
     describe 'github' do
@@ -183,7 +206,7 @@ describe AdminDashboardData do
       let(:enable_setting) { :enable_github_logins }
       let(:key) { :github_client_id }
       let(:secret) { :github_client_secret }
-      it_should_behave_like 'problem detection for login providers'
+      include_examples 'problem detection for login providers'
     end
   end