FIX: Don't reply to Unsubscribe email sent to mailing list mirror

lib/email/receiver.rb

@@ -838,6 +838,8 @@ module Email
 
     def subscription_action_for(body, subject)
       return unless SiteSetting.unsubscribe_via_email
+      return if sent_to_mailinglist_mirror?
+
       if ([subject, body].compact.map(&:to_s).map(&:downcase) & ['unsubscribe']).any?
         :confirm_unsubscribe
       end

spec/components/email/receiver_spec.rb

@@ -1103,6 +1103,13 @@ describe Email::Receiver do
         expect { process(:mailinglist_reply) }.to change { topic.posts.count }
       end
     end
+
+    it "ignores unsubscribe email" do
+      SiteSetting.unsubscribe_via_email = true
+      Fabricate(:user, email: "alice@foo.com")
+
+      expect { process("mailinglist_unsubscribe") }.to_not change { ActionMailer::Base.deliveries.count }
+    end
   end
 
   it "tries to fix unparsable email addresses in To and CC headers" do