title: Does PHP's built-in filter_input work correctly?
body: <p>I tried PHP's built-in function: <strong>filter_input()</strong></p>
  
  <pre><code>var_dump(filter_var('john.doe.@gmail.com', FILTER_VALIDATE_EMAIL));
  </code></pre>
  
  <p>Output:</p>
  
  <blockquote>
    <p>string(19) "john.doe.@gmail.com" </p>
  </blockquote>
  
  <p>Then I tried the latest release of Zend Framework (1.11.3):</p>
  
  <pre><code>$validator = new Zend_Validate_EmailAddress();  
  if ($validator-&gt;isValid('john.doe.@gmail.com')) {
      echo 'OK';
  } else {
      foreach ($validator-&gt;getMessages() as $message) {
              echo "$message\n";
      }
  }
  </code></pre>
  
  <p>Output:</p>
  
  <blockquote>
    <p>'john.doe.' can not be matched against dot-atom format<br>
    'john.doe.' can not be matched against quoted-string format<br>
    'john.doe.' is no valid local part for email address 'john.doe.@gmail.com'  </p>
  </blockquote>
  
  <p>Either the built-in function should return FALSE or the Zend method 'OK'.</p>
  
  <p>My hubmle question is:<br>
  <strong>Which one is right?</strong></p>