title: Precedence: header in email
body: <p>My web application sends email fairly often, and it sends 3 kinds of emails: initiated by user, in response to an event in the system, and in automatic response to an email received by the application.</p>
  
  <p>I would like to make sure that the third type of email does not get stuck in an endless loop of auto-responders talking to each other.  Currently, I use the header:</p>
  
  <pre><code>Precedence: junk
  </code></pre>
  
  <p>but Yahoo! mail is treating these messages as spam.  This is obviously not ideal, because we would like SOMEBODY to read our auto-response and make a decision on it, just not an out-of-office reply.</p>
  
  <p><strong>What is the best way to send an email without triggering either junk filters or auto-responders?</strong></p>
  
  <pre><code>Precedence: junk?
  
  Precedence: bulk?
  
  Precedence: list?
  
  X-Priority: 2?
  </code></pre>