all form processing must be performed on the forms action page.
Your form on the contact.php page is set to post to the contact 2.php page.<form id="form1" name="form1" method="post" action="contact2.php">
this means that the server validation server behavior must be applied to the contact2.php page to validate the form submission.
see this post for more details:
showpost.php?p=105229&postcount=2