PHP’s FILTER_VALIDATE_EMAIL validates email addresses quickly and easily.
<?php $email = "marc@somehost.com"; if(filter_var($email, FILTER_VALIDATE_EMAIL) === FALSE) { echo $email." is invalid"; } else { echo $email." is valid"; } ?>
Read it all at http://www.phpbuilder.com/columns/marc_plotz10012009.php3?page=2