Add notify_mods_when_user_blocked site setting to control whether moderators get a message when someone is automatically blocked

app/models/site_setting.rb

@@ -67,6 +67,7 @@ class SiteSetting < ActiveRecord::Base
 
   setting(:num_flags_to_block_new_user, 3)
   setting(:num_users_to_block_new_user, 3)
+  setting(:notify_mods_when_user_blocked, true)
 
   # used mainly for dev, force hostname for Discourse.base_url
   # You would usually use multisite for this

app/services/spam_rules_enforcer.rb

@@ -48,7 +48,7 @@ class SpamRulesEnforcer
 
   def punish_user
     Post.transaction do
-      if UserBlocker.block(@user, nil, {message: :too_many_spam_flags})
+      if UserBlocker.block(@user, nil, {message: :too_many_spam_flags}) and SiteSetting.notify_mods_when_user_blocked
         GroupMessage.create(Group[:moderators].name, :user_automatically_blocked, {user: @user, limit_once_per: false})
       end
     end

config/locales/server.en.yml

@@ -505,7 +505,7 @@ en:
     cooldown_minutes_after_hiding_posts: "Number of minutes a user must wait before they can edit a post hidden via flagging"
     num_flags_to_block_new_user: "If a new user's posts get this many spam flags from (n) different users, hide all their posts and prevent future posting. 0 disables this feature."
     num_users_to_block_new_user: "If a new user's posts get (x) spam flags from this many different users, hide all their posts and prevent future posting. 0 disables this feature."
-
+    notify_mods_when_user_blocked: "If a user is automatically blocked, send a message to all moderators."
 
     traditional_markdown_linebreaks: "Use traditional linebreaks in Markdown, which require two trailing spaces for a linebreak"
     post_undo_action_window_mins: "Number of seconds users are allowed to reverse actions on a post (like, flag, etc)"

spec/services/spam_rules_enforcer_spec.rb

@@ -128,6 +128,12 @@ describe SpamRulesEnforcer do
         end
         subject.punish_user
       end
+
+      it "doesn't send a pm to moderators if notify_mods_when_user_blocked is false" do
+        SiteSetting.stubs(:notify_mods_when_user_blocked).returns(false)
+        GroupMessage.expects(:create).never
+        subject.punish_user
+      end
     end
 
     context 'user is already blocked' do