php - 如何阻止服务器发送电子邮件

I made php command loop that send email forever

after close the web tab the server continuing sending me email

how can I stop it?

$x = 1;
while ($x == 1)
{

    echo date("d-m-Y ; H:i:s")."<br />";
    mail("reg@mail.com", "test  - ".date("d-m-Y ; H:i:s"), date("d-m-Y ; H:i:s"), "name@mail.com");

    sleep (60*60); // 30 min

}