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!

spec/components/email/receiver_spec.rb

@@ -795,4 +795,23 @@ describe Email::Receiver do
     end
   end
 
+  context "mailinglist mirror" do
+    before do
+      SiteSetting.block_auto_generated_emails = true
+      SiteSetting.find_related_post_with_key = true
+
+      Fabricate(:mailinglist_mirror_category)
+    end
+
+    it "should allow creating topic even when email is autogenerated" do
+      expect { process(:mailinglist) }.to change { Topic.count }
+    end
+
+    it "should allow replying without reply key" do
+      process(:mailinglist)
+      topic = Topic.last
+
+      expect { process(:mailinglist_reply) }.to change { topic.posts.count }
+    end
+  end
 end

spec/fixtures/emails/mailinglist.eml

@@ -0,0 +1,12 @@
+From: alice@foo.com
+To: list@example.com
+Subject: mailinglist mirror
+Date: Mon, 16 Oct 2017 09:18:32 +0100
+Message-ID: <bddaa334ef93b5f3c7c3a42599330844@foo.com>
+Precedence: list
+List-Id: Example List <list@example.com>
+Content-Transfer-Encoding: 7bit
+Content-Type: text/plain; charset="us-ascii"
+Sender: list-bounces@example.com
+
+I love Discourse's mailinglist mirror feature.

spec/fixtures/emails/mailinglist_reply.eml

@@ -0,0 +1,16 @@
+In-Reply-To: <bddaa334ef93b5f3c7c3a42599330844@foo.com>
+References: <bddaa334ef93b5f3c7c3a42599330844@foo.com>
+From: bob@bar.com
+To: list@example.com
+Subject: Re: mailinglist mirror
+Date: Mon, 16 Oct 2017 09:41:26 +0100
+Message-ID: <CACJSOXnUonfJqMggzKYsZX@bar.com>
+Precedence: list
+List-Id: Example List <list@example.com>
+Content-Transfer-Encoding: 7bit
+Content-Type: text/plain; charset="us-ascii"
+Sender: list-bounces@example.com
+
+> I love Discourse's mailinglist mirror feature.
+
+Me too!