FEATURE: do not send notification emails to users who are included in the To and CC header of an incoming email

spec/fabricators/incoming_email_fabricator.rb

@@ -1 +1,20 @@
-Fabricator(:incoming_email)
+Fabricator(:incoming_email) do
+  message_id "12345@example.com"
+  subject "Hello world"
+  from_address "foo@example.com"
+  to_addresses "someone@else.com"
+
+  raw <<~RAW
+    Return-Path: <foo@example.com>
+    From: Foo <foo@example.com>
+    To: someone@else.com
+    Subject: Hello world
+    Date: Fri, 15 Jan 2016 00:12:43 +0100
+    Message-ID: <12345@example.com>
+    Mime-Version: 1.0
+    Content-Type: text/plain; charset=UTF-8
+    Content-Transfer-Encoding: quoted-printable
+
+    The body contains "Hello world" too.
+  RAW
+end

spec/fabricators/post_fabricator.rb

@@ -133,3 +133,14 @@ Fabricator(:private_message_post, from: :post) do
   end
   raw "Ssshh! This is our secret conversation!"
 end
+
+Fabricator(:post_via_email, from: :post) do
+  incoming_email
+  via_email true
+
+  after_create do |post|
+    incoming_email.topic = post.topic
+    incoming_email.post = post
+    incoming_email.user = post.user
+  end
+end