<?php
$email = $_user['email'];//这是邮箱，指定要修改


$em = explode("@",$email);
$name = $em[0];
$len = strlen($name);
$showLen = floor($len/2);
$str_arr = str_split($name);
for($ii=$showLen;$ii<$len;$ii++){
    $str_arr[$ii] = '*';
}
$em[0] = implode('',$str_arr);
$new_name = implode('@',$em);
echo $new_name;?>