title: How to configure a jenkins job to send mail if a SCM commit
body: <p>I have problems with configuring a jenkins job that need to do the following task :</p>
  
  <ul>
  <li>scheduled every 30 minutes => OK</li>
  <li>do an update (CVS, SVN, ...) => OK</li>
  <li>send an email if a change is detected in the SCM repo => KO</li>
  </ul>
  
  <p>So my job is configured as follow :</p>
  
  <ul>
  <li>Source Code Management : cvs root / branch / ...</li>
  <li>Build Triggers : Poll SCM : */30 * * * *</li>
  <li>Build : No buils step</li>
  <li>Post-build Actions : E-mail Notification</li>
  </ul>
  
  <p>But I received emails only when the build failed and not when an update is detected.</p>
  
  <p>Any hint ?</p>