Example of email validation using the XmlHttpRequest object. The email address is validated in real time as a background operation while the client continues to fill out the form without any page reload. The email validation is conducted by a PHP script which connects to and interogates the remote mail server. Give it a try. Enter an email address in the first box then tab to the second box. In a real application only the warning is necessary so if the email returns valid do nothing.

Enter an email

Now tab here