title: Validating email address - stopping double dots
body: <p>I am currently <a href="http://swiftmailer.org/" rel="nofollow">SwiftMailer</a> to send out emails. I have a seperate email validation script that checks emails to ensure they are valid before using SwiftMailer to send. It works pretty well.</p>
  
  <p>However, my validator doesn't pick up accidental double dots (..) in email addresses like:</p>
  
  <p>ben..sinclair@email.com
  OR
  ben.sinclair@email..com</p>
  
  <p>Here's my code... what would I need to add in to give an error if they put double dots anywhere in the email address?</p>
  
  <pre><code>function valid_email($email) {
      if (preg_match("/[_a-z0-9-]+(\.[_a-z0-9-]+)*@([_0-9a-z][_0-9a-z-]*[_0-9a-z]\.)+[0-9a-z][a-z]+/", $email, $matches))
          return true;
      return false;
  }
  </code></pre>