title: Jenkins : sending email notification when starting a build
body: <p>In Jenkins, Is there a way to send a mail when starting a build. 
  I know there is a post-build email notification which sends mail to the given recipients after a successful or failure build. Similarly i am expecting something like pre build notification. </p>
  
  <p>Also is there a conditional email like if username == null send to xyz@domain.com else send it to requestor.</p>
  
  <p>Tried : couple of plugins but didn't help much as they were post-build plugins </p>