title: Regexp for spam filter
body: <p>I've trying to set up some filters from spam mail on our Microsoft Exchange server.</p>
  
  <p>I need to check the letter ad spam if there is in header "Recieved" more then 3 dots and it doesn't containt word "outlook"</p>
  
  <p>Checking dots can be done by regex <code>.*\..*\..*\..*</code></p>
  
  <p>Checking if string doesn't contain word "outlook" can be done by regex <code>((?!outlook).)*$</code></p>
  
  <p>I try to unite then in one expression <code>^(?=.*\..*\..*\..*)(?=((?!outlook).)*$)</code> but doesn't work:(</p>
  
  <p>What am I doing wrong?</p>