title: Jenkins email-ext plugin, pre-send scripts:
body: <p>We use <code>Jenkins</code> as our ci server, and we run integration test on firefox on <code>xvfb</code>. Sometime, we receive the email about test failure, caused by <code>xvfb</code> starting failed. </p>
  
  <p>So we want to ignore sending email by this case. As we know, the <code>email-ext</code> plugin can help us. we should write <code>pre-send scripts</code>, but we don't know how to write them.</p>
  
  <p>How do I write a script to cancel sending email when failure output message contains a specified error message?</p>