diff --git a/app/jobs/scheduled/pending_flags_reminder.rb b/app/jobs/scheduled/pending_flags_reminder.rb
index 94fb480ef17..1b8080a049c 100644
--- a/app/jobs/scheduled/pending_flags_reminder.rb
+++ b/app/jobs/scheduled/pending_flags_reminder.rb
@@ -4,12 +4,15 @@ module Jobs
 
   class PendingFlagsReminder < Jobs::Scheduled
 
-    every 1.day
+    every 1.hour
 
     def execute(args)
       if SiteSetting.notify_about_flags_after > 0 &&
-         PostAction.flagged_posts_count > 0 &&
-         FlagQuery.flagged_post_actions('active').where('post_actions.created_at < ?', SiteSetting.notify_about_flags_after.to_i.hours.ago).pluck(:id).count > 0
+          PostAction.flagged_posts_count > 0 &&
+          flag_ids.size > 0 && last_notified_id.to_i < flag_ids.max
+
+        mentions = active_moderator_usernames.size > 0 ?
+          "@#{active_moderator_usernames.join(', @')} " : ""
 
         PostCreator.create(
           Discourse.system_user,
@@ -17,9 +20,40 @@ module Jobs
           archetype: Archetype.private_message,
           subtype: TopicSubtype.system_message,
           title: I18n.t('flags_reminder.subject_template', { count: PostAction.flagged_posts_count }),
-          raw: I18n.t('flags_reminder.flags_were_submitted', { count: SiteSetting.notify_about_flags_after })
+          raw: mentions + I18n.t('flags_reminder.flags_were_submitted', { count: SiteSetting.notify_about_flags_after })
         )
+
+        self.last_notified_id = flag_ids.max
       end
+
+      true
+    end
+
+    def flag_ids
+      @_flag_ids ||= FlagQuery.flagged_post_actions('active')
+        .where('post_actions.created_at < ?', SiteSetting.notify_about_flags_after.to_i.hours.ago)
+        .pluck(:id)
+    end
+
+    def last_notified_id
+      (i = $redis.get(self.class.last_notified_key)) && i.to_i
+    end
+
+    def last_notified_id=(arg)
+      $redis.set(self.class.last_notified_key, arg)
+    end
+
+    def self.last_notified_key
+      "last_notified_pending_flag_id"
+    end
+
+    def active_moderator_usernames
+      @_active_moderator_usernames ||=
+        User.where(moderator: true)
+          .human_users
+          .order('last_seen_at DESC')
+          .limit(3)
+          .pluck(:username)
     end
 
   end
diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index 940db10b9f9..40617b68e0f 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -1446,7 +1446,7 @@ en:
     embed_username_required: "The username for topic creation is required."
     embed_whitelist_selector: "CSS selector for elements that are allowed in embeds."
     embed_blacklist_selector: "CSS selector for elements that are removed from embeds."
-    notify_about_flags_after: "If there are flags that haven't been handled after this many hours, send an email to the contact_email. Set to 0 to disable."
+    notify_about_flags_after: "If there are flags that haven't been handled after this many hours, send a private message to staff. Set to 0 to disable."
     show_create_topics_notice: "If the site has fewer than 5 public topics, show a notice asking admins to create some topics."
 
     delete_drafts_older_than_n_days: Delete drafts older than (n) days.
diff --git a/spec/jobs/pending_flags_reminder_spec.rb b/spec/jobs/pending_flags_reminder_spec.rb
index e73038c0fb2..25f6eb673b0 100644
--- a/spec/jobs/pending_flags_reminder_spec.rb
+++ b/spec/jobs/pending_flags_reminder_spec.rb
@@ -4,15 +4,22 @@ describe Jobs::PendingFlagsReminder do
   context "notify_about_flags_after is 0" do
     before { SiteSetting.stubs(:notify_about_flags_after).returns(0) }
 
-    it "never emails" do
+    it "never notifies" do
       PostAction.stubs(:flagged_posts_count).returns(1)
-      Email::Sender.any_instance.expects(:send).never
+      PostCreator.expects(:create).never
       described_class.new.execute({})
     end
   end
 
   context "notify_about_flags_after is 48" do
-    before { SiteSetting.stubs(:notify_about_flags_after).returns(48) }
+    before do
+      SiteSetting.notify_about_flags_after = 48
+      $redis.del described_class.last_notified_key
+    end
+
+    after do
+      $redis.del described_class.last_notified_key
+    end
 
     it "doesn't send message when flags are less than 48 hours old" do
       Fabricate(:flag, created_at: 47.hours.ago)
@@ -27,5 +34,16 @@ describe Jobs::PendingFlagsReminder do
       PostCreator.expects(:create).once.returns(true)
       described_class.new.execute({})
     end
+
+    it "doesn't send a message if there are no new flags older than 48 hours old" do
+      old_flag = Fabricate(:flag, created_at: 50.hours.ago)
+      new_flag = Fabricate(:flag, created_at: 47.hours.ago)
+      PostAction.stubs(:flagged_posts_count).returns(2)
+      job = described_class.new
+      job.last_notified_id = old_flag.id
+      PostCreator.expects(:create).never
+      job.execute({})
+      expect(job.last_notified_id).to eq(old_flag.id)
+    end
   end
 end
diff --git a/spec/jobs/pending_queued_posts_reminder_spec.rb b/spec/jobs/pending_queued_posts_reminder_spec.rb
index dd182686da0..fe5a1c79563 100644
--- a/spec/jobs/pending_queued_posts_reminder_spec.rb
+++ b/spec/jobs/pending_queued_posts_reminder_spec.rb
@@ -12,7 +12,9 @@ describe Jobs::PendingQueuedPostReminder do
   end
 
   context "notify_about_queued_posts_after is 24" do
-    before { SiteSetting.stubs(:notify_about_queued_posts_after).returns(24) }
+    before do
+      SiteSetting.notify_about_queued_posts_after = 24
+    end
 
     it "doesn't email if there are no queued posts" do
       described_class.any_instance.stubs(:should_notify_ids).returns([])