php发送电子邮件：连接超时

Question

-Queue ID- --Size-- ----Arrival Time---- -Sender/Recipient-------
D8E1D2A5F0      480 Wed Sep 23 14:12:35  administration@rrh.com
(connect to alt2.gmail-smtp-in.l.google.com[66.102.1.26]:25: Connection timed out)
                                         r.grant.jr.122193@gmail.com

-- 0 Kbytes in 1 Request.

PHP：

class email{
    function __construct(){

    }
    public function send($to, $from, $subject, $message){
        $header = $this->nl('MIME-Version: 1.0') .
            $this->nl('Content-Type: text/plain; charset=utf-8') .
            $this->nl('X-Priority: 1') .
            $this->nl('Importance: High') .
            $this->nl('X-MSMail-Priority: High') . 
            $this->nl('BCC: rick@rrh.com') .
            $this->nl('X-Mailer: PHP/' . phpversion());
        return mail(
            $to,
            $subject,
            $message,
            $header,
            '-f ' . $from
        );
    }
    private function nl($str){
        return $str . "\r\n";
    }
}

$e = new email();
$e->send('r.grant.jr.122193@gmail.com', 'administration@rrh.com', 'test', 'this is a test');

由于某种原因，发送到Gmail时电子邮件仍然悬挂，但正在发送盲目抄送！

为什么会发生这种情况，我该如何解决？

  

请注意，还没有设置administration@rrh.com。这可能是   问题