don't send more than 1 reply per day to auto-generated emails

config/locales/server.en.yml

@@ -73,7 +73,6 @@ en:
         topic_not_found_error: "Happens when a reply came in but the related topic has been deleted."
         topic_closed_error: "Happens when a reply came in but the related topic has been closed."
         bounced_email_error: "Email is a bounced email report."
-        auto_generated_email_reply: "Email contains a reply to an auto generated email."
         screened_email_error: "Happens when the sender's email address was already screened."
 
   errors: &errors

lib/email/message_builder.rb

@@ -17,9 +17,6 @@ module Email
   class MessageBuilder
     attr_reader :template_args
 
-    REPLY_TO_AUTO_GENERATED_HEADER_KEY = "X-Discourse-Reply-to-Auto-Generated".freeze
-    REPLY_TO_AUTO_GENERATED_HEADER_VALUE = "marked".freeze
-
     def initialize(to, opts=nil)
       @to = to
       @opts = opts || {}
@@ -138,10 +135,6 @@ module Email
         result['List-Unsubscribe'] = "<#{template_args[:user_preferences_url]}>"
       end
 
-      if @opts[:mark_as_reply_to_auto_generated]
-        result[REPLY_TO_AUTO_GENERATED_HEADER_KEY] = REPLY_TO_AUTO_GENERATED_HEADER_VALUE
-      end
-
       result['X-Discourse-Post-Id'] = @opts[:post_id].to_s if @opts[:post_id]
       result['X-Discourse-Topic-Id'] = @opts[:topic_id].to_s if @opts[:topic_id]
 

lib/email/processor.rb

@@ -15,16 +15,14 @@ module Email
         receiver = Email::Receiver.new(@mail)
         receiver.process!
       rescue Email::Receiver::BouncedEmailError => e
+        # never reply to bounced emails
         log_email_process_failure(@mail, e)
         set_incoming_email_rejection_message(receiver.incoming_email, I18n.t("emails.incoming.errors.bounced_email_error"))
-      rescue Email::Receiver::AutoGeneratedEmailReplyError => e
-        log_email_process_failure(@mail, e)
-        set_incoming_email_rejection_message(receiver.incoming_email, I18n.t("emails.incoming.errors.auto_generated_email_reply"))
       rescue => e
         log_email_process_failure(@mail, e)
-
+        incoming_email = receiver.try(:incoming_email)
-        rejection_message = handle_failure(@mail, e)
+        rejection_message = handle_failure(@mail, e, incoming_email)
-        if rejection_message.present? && receiver && (incoming_email = receiver.incoming_email)
+        if rejection_message.present?
           set_incoming_email_rejection_message(incoming_email, rejection_message.body.to_s)
         end
       end
@@ -32,7 +30,7 @@ module Email
 
     private
 
-    def handle_failure(mail_string, e)
+    def handle_failure(mail_string, e, incoming_email)
       message_template = case e
         when Email::Receiver::EmptyEmailError             then :email_reject_empty
         when Email::Receiver::NoBodyDetectedError         then :email_reject_empty
@@ -67,10 +65,6 @@ module Email
         template_args[:rate_limit_description] = e.description
       end
 
-      if message_template == :email_reject_auto_generated
-        template_args[:mark_as_reply_to_auto_generated] = true
-      end
-
       if message_template
         # inform the user about the rejection
         message = Mail::Message.new(mail_string)
@@ -79,7 +73,11 @@ module Email
         template_args[:site_name] = SiteSetting.title
 
         client_message = RejectionMailer.send_rejection(message_template, message.from, template_args)
-        Email::Sender.new(client_message, message_template).send
+
+        # don't send more than 1 reply per day to auto-generated emails
+        if !incoming_email.try(:is_auto_generated) || can_reply_to_auto_generated?(message.from)
+          Email::Sender.new(client_message, message_template).send
+        end
       else
         Rails.logger.error("Unrecognized error type (#{e}) when processing incoming email\n\nMail:\n#{mail_string}")
       end
@@ -87,6 +85,17 @@ module Email
       client_message
     end
 
+    def can_reply_to_auto_generated?(email)
+      key = "auto_generated_reply:#{email}:#{Date.today}"
+
+      if $redis.setnx(key, "1")
+        $redis.expire(key, 25.hours)
+        true
+      else
+        false
+      end
+    end
+
     def set_incoming_email_rejection_message(incoming_email, message)
       incoming_email.update_attributes!(rejection_message: message)
     end

lib/email/receiver.rb

@@ -13,7 +13,6 @@ module Email
     class ScreenedEmailError           < ProcessingError; end
     class UserNotFoundError            < ProcessingError; end
     class AutoGeneratedEmailError      < ProcessingError; end
-    class AutoGeneratedEmailReplyError < ProcessingError; end
     class BouncedEmailError            < ProcessingError; end
     class NoBodyDetectedError          < ProcessingError; end
     class InactiveUserError            < ProcessingError; end
@@ -82,8 +81,7 @@ module Email
 
       if is_auto_generated?
         @incoming_email.update_columns(is_auto_generated: true)
-        raise AutoGeneratedEmailReplyError if check_reply_to_auto_generated_header
+        raise AutoGeneratedEmailError if SiteSetting.block_auto_generated_emails?
-        raise AutoGeneratedEmailError      if SiteSetting.block_auto_generated_emails?
       end
 
       if action = subscription_action_for(body, subject)
@@ -151,20 +149,20 @@ module Email
         if bounce_key && (email_log = EmailLog.find_by(bounce_key: bounce_key))
           email_log.update_columns(bounced: true)
           email = email_log.user.try(:email) || @from_email
-          if email.present?
+          if email.present? && @mail.error_status.present?
-            if @mail.error_status.present?
+            if @mail.error_status.start_with?("4.")
-              if @mail.error_status.start_with?("4.")
+              Email::Receiver.update_bounce_score(email, SOFT_BOUNCE_SCORE)
-                Email::Receiver.update_bounce_score(email, SOFT_BOUNCE_SCORE)
+            else @mail.error_status.start_with?("5.")
-              elsif @mail.error_status.start_with?("5.")
-                Email::Receiver.update_bounce_score(email, HARD_BOUNCE_SCORE)
-              end
-            elsif is_auto_generated?
               Email::Receiver.update_bounce_score(email, HARD_BOUNCE_SCORE)
             end
           end
         end
       end
 
+      if is_auto_generated?
+        Email::Receiver.update_bounce_score(@from_email, SOFT_BOUNCE_SCORE)
+      end
+
       true
     end
 
@@ -534,20 +532,6 @@ module Email
       !topic.topic_allowed_groups.where("group_id IN (SELECT group_id FROM group_users WHERE user_id = ?)", user.id).exists?
     end
 
-    private
-
-    def check_reply_to_auto_generated_header
-      headers = Mail::Header.new(@mail.body.to_s.gsub("\r\n\r\n", "\r\n")).to_a
-
-      index = headers.find_index do |f|
-        f.name == Email::MessageBuilder::REPLY_TO_AUTO_GENERATED_HEADER_KEY
-      end
-
-      if index
-        headers[index].value == Email::MessageBuilder::REPLY_TO_AUTO_GENERATED_HEADER_VALUE
-      end
-    end
-
   end
 
 end

spec/components/email/message_builder_spec.rb

@@ -142,7 +142,6 @@ describe Email::MessageBuilder do
         body: 'hello world',
         topic_id: 1234,
         post_id: 4567,
-        mark_as_reply_to_auto_generated: true
       )
     end
 
@@ -154,12 +153,6 @@ describe Email::MessageBuilder do
       expect(message_with_header_args.header_args['X-Discourse-Topic-Id']).to eq('1234')
     end
 
-    it "marks the email as replying to an auto generated email" do
-      expect(message_with_header_args.header_args[
-        Email::MessageBuilder::REPLY_TO_AUTO_GENERATED_HEADER_KEY
-      ]).to eq(Email::MessageBuilder::REPLY_TO_AUTO_GENERATED_HEADER_VALUE)
-    end
-
   end
 
   context "unsubscribe link" do

spec/components/email/receiver_spec.rb

@@ -61,10 +61,6 @@ describe Email::Receiver do
     expect(IncomingEmail.last.is_bounce).to eq(true)
   end
 
-  it "raises an AutoGeneratedEmailReplyError when email contains a marked reply" do
-    expect { process(:bounced_email_2) }.to raise_error(Email::Receiver::AutoGeneratedEmailReplyError)
-  end
-
   context "bounces to VERP" do
 
     let(:bounce_key) { "14b08c855160d67f2e0c2f8ef36e251e" }

spec/fixtures/emails/bounced_email_2.eml

@@ -1,29 +0,0 @@
-Delivered-To: someguy@discourse.org
-Date: Thu,  7 Apr 2016 19:04:30 +0900 (JST)
-From: MAILER-DAEMON@b-s-c.co.jp (Mail Delivery System)
-Subject: Undelivered Mail Returned to Sender
-To: someguy@discourse.org
-MIME-Version: 1.0
-Content-Type: multipart/report; report-type=delivery-status;
-    boundary="18F5D18A0075.1460023470/some@daemon.com"
-
-This is a MIME-encapsulated message.
-
---18F5D18A0075.1460023470/some@daemon.com
-Content-Description: Notification
-Content-Type: text/plain; charset=us-ascii
-
-Your email bounced
-
---18F5D18A0075.1460023470/some@daemon.com
-Content-Description: Undelivered Message
-Content-Type: message/rfc822
-
-Return-Path: <someguy@discourse.org>
-Date: Thu, 07 Apr 2016 03:04:28 -0700 (PDT)
-From: someguy@discourse.org
-X-Discourse-Reply-to-Auto-Generated: marked
-
-This is the body
-
---18F5D18A0075.1460023470/some@daemon.com--

spec/jobs/poll_mailbox_spec.rb

@@ -90,15 +90,6 @@ describe Jobs::PollMailbox do
       )
     end
 
-    it "does not reply to an email containing a reply to an auto generated email" do
-      expect { process_popmail(:bounced_email_2) }.to_not change { ActionMailer::Base.deliveries.count }
-
-      incoming_email = IncomingEmail.last
-
-      expect(incoming_email.rejection_message).to eq(
-        I18n.t("emails.incoming.errors.auto_generated_email_reply")
-      )
-    end
   end
 
 end