/**
 * 邮箱地址正则表达式
 */
$preg = '/^(\w{1,25})@(\w{1,16})(\.(\w{1,4})){1,3}$/';
$b = 'ffgddayasdadasdf@gmialsdfsdfasd3.com.cn.org';
if(preg_match($preg, $b)){
    echo "匹配到了";
}else{
    echo "没有匹配到";
}