UserEmailObserver is now removed

no big surprises here was pretty straightforward

after_commit semantics sure are weird though

app/services/notification_emailer.rb

@@ -0,0 +1,124 @@
+class NotificationEmailer
+
+  class EmailUser
+    attr_reader :notification
+
+    def initialize(notification)
+      @notification = notification
+    end
+
+    def group_mentioned
+      enqueue :group_mentioned
+    end
+
+    def mentioned
+      enqueue :user_mentioned
+    end
+
+    def posted
+      enqueue :user_posted
+    end
+
+    def quoted
+      enqueue :user_quoted
+    end
+
+    def replied
+      enqueue :user_replied
+    end
+
+    def linked
+      enqueue :user_linked
+    end
+
+    def watching_first_post
+      enqueue :user_watching_first_post
+    end
+
+    def private_message
+      enqueue_private(:user_private_message)
+    end
+
+    def invited_to_private_message
+      enqueue(:user_invited_to_private_message, private_delay)
+    end
+
+    def invited_to_topic
+      enqueue(:user_invited_to_topic, private_delay)
+    end
+
+    def self.notification_params(notification, type)
+      post_id = (notification.data_hash[:original_post_id] || notification.post_id).to_i
+
+      hash = {
+        type: type,
+        user_id: notification.user_id,
+        notification_id: notification.id,
+        notification_data_hash: notification.data_hash,
+        notification_type: Notification.types[notification.notification_type],
+      }
+
+      hash[:post_id] = post_id if post_id > 0
+      hash
+    end
+
+    private
+
+    EMAILABLE_POST_TYPES ||= Set.new [Post.types[:regular], Post.types[:whisper]]
+
+    def enqueue(type, delay=default_delay)
+      return unless notification.user.user_option.email_direct?
+      perform_enqueue(type, delay)
+    end
+
+    def enqueue_private(type, delay=private_delay)
+      return unless notification.user.user_option.email_private_messages?
+      perform_enqueue(type, delay)
+    end
+
+    def perform_enqueue(type, delay)
+      user = notification.user
+      return unless user.active? || user.staged?
+      return if SiteSetting.must_approve_users? && !user.approved?
+
+      return unless EMAILABLE_POST_TYPES.include?(post_type)
+
+      Jobs.enqueue_in(delay, :user_email, self.class.notification_params(notification, type))
+    end
+
+    def default_delay
+      SiteSetting.email_time_window_mins.minutes
+    end
+
+    def private_delay
+      SiteSetting.private_email_time_window_seconds
+    end
+
+    def post_type
+      @post_type ||= begin
+        type = notification.data_hash["original_post_type"] if notification.data_hash
+        type ||= notification.post.try(:post_type)
+        type
+      end
+    end
+
+  end
+
+  def self.disable
+    @disabled = true
+  end
+
+  def self.enable
+    @disabled = false
+  end
+
+  def self.process_notification(notification)
+    return if @disabled
+
+    email_user   = EmailUser.new(notification)
+    email_method = Notification.types[notification.notification_type]
+
+    email_user.send(email_method) if email_user.respond_to? email_method
+  end
+
+end