- str_replace: documentation ( source)
<?php
$email = 'johnsnow@ヒキワリ.ナットウ.ニホン';
//$email = idn_to_ascii($email);
$email = str_replace('xn--', '', $email);
echo $email;
//echo "\n";
//$email = 'johnsnow@zoosk.com';
//$email = idn_to_ascii($email);
//$email = str_replace('xn--', '', $email);
//echo $email;
?>