ignore some site settings for emails sent to mailinglist mirror category

lib/email/receiver.rb

@@ -105,7 +105,10 @@ module Email
 
       if is_auto_generated?
         @incoming_email.update_columns(is_auto_generated: true)
-        raise AutoGeneratedEmailError if SiteSetting.block_auto_generated_emails?
+
+        if SiteSetting.block_auto_generated_emails? && !sent_to_mailinglist_mirror?
+          raise AutoGeneratedEmailError
+        end
       end
 
       if action = subscription_action_for(body, subject)
@@ -374,9 +377,20 @@ module Email
     end
 
     def destinations
-      all_destinations
+      @destinations ||= all_destinations
         .map { |d| Email::Receiver.check_address(d) }
-        .drop_while(&:blank?)
+        .reject(&:blank?)
+    end
+
+    def sent_to_mailinglist_mirror?
+      destinations.each do |destination|
+        next unless destination[:type] == :category
+
+        category = destination[:obj]
+        return true if category.mailinglist_mirror?
+      end
+
+      false
     end
 
     def self.check_address(address)
@@ -573,7 +587,7 @@ module Email
     end
 
     def find_related_post
-      return if SiteSetting.find_related_post_with_key
+      return if SiteSetting.find_related_post_with_key && !sent_to_mailinglist_mirror?
 
       message_ids = [@mail.in_reply_to, Email::Receiver.extract_references(@mail.references)]
       message_ids.flatten!