FIX: email replies should not be accepted for deleted topics

app/jobs/scheduled/poll_mailbox.rb

@@ -45,6 +45,8 @@ module Jobs
           message_template = :email_reject_reply_key
         when Email::Receiver::BadDestinationAddress
           message_template = :email_reject_destination
+        when Email::Receiver::TopicNotFoundError
+          message_template = :email_reject_topic_not_found
         when Email::Receiver::TopicClosedError
           message_template = :email_reject_topic_closed
         when ActiveRecord::Rollback

config/locales/server.en.yml

@@ -1523,6 +1523,13 @@ en:
 
         None of the destination addresses are recognized. Please make sure that the site address is in the To: line (not Cc: or Bcc:), and that you are sending to the correct email address provided by staff.
 
+    email_reject_topic_not_found:
+      subject_template: "Email issue -- Topic Not Found"
+      text_body_template: |
+        We're sorry, but your email message to %{destination} (titled %{former_title}) didn't work.
+
+        The topic is not found, it may have been deleted. If you believe this is in error, contact a staff member.
+
     email_reject_topic_closed:
       subject_template: "Email issue -- Topic Closed"
       text_body_template: |

lib/email/receiver.rb

@@ -15,6 +15,7 @@ module Email
     class UserNotFoundError < ProcessingError; end
     class UserNotSufficientTrustLevelError < ProcessingError; end
     class BadDestinationAddress < ProcessingError; end
+    class TopicNotFoundError < ProcessingError; end
     class TopicClosedError < ProcessingError; end
     class EmailLogNotFound < ProcessingError; end
     class InvalidPost < ProcessingError; end
@@ -69,6 +70,7 @@ module Email
         @email_log = dest_info[:obj]
 
         raise EmailLogNotFound if @email_log.blank?
+        raise TopicNotFoundError if Topic.find_by_id(@email_log.topic_id).nil?
         raise TopicClosedError if Topic.find_by_id(@email_log.topic_id).closed?
 
         create_reply

spec/components/email/receiver_spec.rb

@@ -253,6 +253,37 @@ Pleasure to have you here!
     end
   end
 
+  describe "posting reply to a deleted topic" do
+    let(:reply_key) { raise "Override this in a lower describe block" }
+    let(:email_raw) { raise "Override this in a lower describe block" }
+    let(:receiver) { Email::Receiver.new(email_raw) }
+    let(:deleted_topic) { Fabricate(:deleted_topic) }
+    let(:post) { Fabricate(:post, topic: deleted_topic, post_number: 1) }
+    let(:replying_user_email) { 'jake@adventuretime.ooo' }
+    let(:replying_user) { Fabricate(:user, email: replying_user_email, trust_level: 2) }
+    let(:email_log) { EmailLog.new(reply_key: reply_key,
+                                   post: post,
+                                   post_id: post.id,
+                                   topic_id: deleted_topic.id,
+                                   email_type: 'user_posted',
+                                   user: replying_user,
+                                   user_id: replying_user.id,
+                                   to_address: replying_user_email
+    ) }
+
+    before do
+      email_log.save
+    end
+
+    describe "should not create post" do
+      let!(:reply_key) { '59d8df8370b7e95c5a49fbf86aeb2c93' }
+      let!(:email_raw) { fixture_file("emails/valid_reply.eml") }
+      it "raises a TopicNotFoundError" do
+        expect { receiver.process }.to raise_error(Email::Receiver::TopicNotFoundError)
+      end
+    end
+  end
+
   describe "posting a new topic" do
     let(:category_destination) { raise "Override this in a lower describe block" }
     let(:email_raw) { raise "Override this in a lower describe block" }

spec/jobs/poll_mailbox_spec.rb

@@ -232,6 +232,31 @@ describe Jobs::PollMailbox do
       end
     end
 
+    describe "when topic is deleted" do
+      let(:email) { MockPop3EmailObject.new fixture_file('emails/valid_reply.eml')}
+      let(:deleted_topic) { Fabricate(:deleted_topic) }
+      let(:first_post) { Fabricate(:post, topic: deleted_topic, post_number: 1)}
+
+      before do
+        first_post.save
+        EmailLog.create(to_address: 'jake@email.example.com',
+                        email_type: 'user_posted',
+                        reply_key: '59d8df8370b7e95c5a49fbf86aeb2c93',
+                        user: user,
+                        post: first_post,
+                        topic: deleted_topic)
+      end
+
+      describe "should not create post" do
+        it "raises a TopicNotFoundError" do
+          expect_exception Email::Receiver::TopicNotFoundError
+
+          poller.handle_mail(email)
+          email.should be_deleted
+        end
+      end
+    end
+
     describe "in failure conditions" do
 
       it "a valid reply without an email log raises an EmailLogNotFound error" do