FEATURE: handle bounced emails

lib/email/receiver.rb

@@ -56,10 +56,6 @@ module Email
     end
 
     def process_internal
-      # temporarily disable processing automated replies to VERP
-      return if @mail.destinations.any? { |to| to[/\+verp-\h{32}@/i] }
-
-      raise BouncedEmailError  if @mail.bounced? && !@mail.retryable?
       raise ScreenedEmailError if ScreenedEmail.should_block?(@from_email)
 
       user = find_or_create_user(@from_email, @from_display_name)
@@ -68,6 +64,7 @@ module Email
 
       @incoming_email.update_columns(user_id: user.id)
 
+      raise BouncedEmailError if is_bounce?
       raise InactiveUserError if !user.active && !user.staged
       raise BlockedUserError  if user.blocked
 
@@ -132,6 +129,61 @@ module Email
       end
     end
 
+    SOFT_BOUNCE_SCORE ||= 1
+    HARD_BOUNCE_SCORE ||= 2
+
+    def is_bounce?
+      return false unless @mail.bounced? || verp
+
+      @incoming_email.update_columns(is_bounce: true)
+
+      if verp
+        bounce_key = verp[/\+verp-(\h{32})@/, 1]
+        if bounce_key && (email_log = EmailLog.find_by(bounce_key: bounce_key))
+          email_log.update_columns(bounced: true)
+
+          if @mail.error_status.present?
+            if @mail.error_status.start_with?("4.")
+              update_bounce_score(email_log.user.email, SOFT_BOUNCE_SCORE)
+            elsif @mail.error_status.start_with?("5.")
+              update_bounce_score(email_log.user.email, HARD_BOUNCE_SCORE)
+            end
+          end
+        end
+      end
+
+      true
+    end
+
+    def verp
+      @verp ||= @mail.destinations.select { |to| to[/\+verp-\h{32}@/] }.first
+    end
+
+    def update_bounce_score(email, score)
+      # only update bounce score once per day
+      key = "bounce_score:#{email}:#{Date.today}"
+
+      if $redis.setnx(key, "1")
+        $redis.expire(key, 25.hours)
+
+        if user = User.find_by(email: email)
+          user.user_stat.bounce_score += score
+          user.user_stat.reset_bounce_score_after = 30.days.from_now
+          user.user_stat.save
+
+          if user.active && user.user_stat.bounce_score >= SiteSetting.bounce_score_threshold
+            user.deactivate
+            StaffActionLogger.new(Discourse.system_user).log_revoke_email(user)
+            EmailToken.where(email: user.email, confirmed: true).update_all(confirmed: false)
+          end
+        end
+
+        true
+      else
+        false
+      end
+    end
+
     def is_auto_generated?
       return false if SiteSetting.auto_generated_whitelist.split('|').include?(@from_email)
       @mail[:precedence].to_s[/list|junk|bulk|auto_reply/i] ||