...uno a caso (preso dal sito della zend)
<?php
$email="john@zend.com";
if(!eregi("^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-
]+)*(\.[a-z]{2,3})$", $email) {
echo "The e-mail was not valid";
} else {
echo "The e-mail was valid";
}
?>
M