PHPMailer：我是否连接到外部 SMTP？

Question

我得到了以下由 PHPMailer 输出的日志：

2020-02-03 13:39:00 Connection: opening to some-external.smtp.host:25, timeout=300, options=array()
2020-02-03 13:39:00 Connection: opened
2020-02-03 13:39:00 SERVER -> CLIENT: 220-my-own.domain.com ESMTP Exim 4.92 #2 Mon, 03 Feb 2020 13:39:00 +0000 220-We do not authorize the use of this system to transport unsolicited, 220 and/or bulk e-mail.
2020-02-03 13:39:00 CLIENT -> SERVER: EHLO url-at-my-own.domain.com
2020-02-03 13:39:00 SERVER -> CLIENT: 250-url-at-my-own.domain.com Hello url-at-my-own.domain.com [31.186.175.24]250-SIZE 52428800250-8BITMIME250-PIPELINING250-AUTH PLAIN LOGIN250-STARTTLS250 HELP
2020-02-03 13:39:00 CLIENT -> SERVER: MAIL FROM:<info@domain.com>
2020-02-03 13:39:00 SERVER -> CLIENT: 250 OK
2020-02-03 13:39:00 CLIENT -> SERVER: RCPT TO:<recipient@hotmail.com>
2020-02-03 13:39:00 SERVER -> CLIENT: 550-Please turn on SMTP Authentication in your mail client. 550-(test.admin.mijnvolksuniversiteit.nl) [31.186.175.24]:50402 is not550 permitted to relay through this server without authentication.
2020-02-03 13:39:00 SMTP ERROR: RCPT TO command failed: 550-Please turn on SMTP Authentication in your mail client. 550-(url-at-my-own.domain.com) [31.186.175.24]:50402 is not550 permitted to relay through this server without authentication.
2020-02-03 13:39:00 CLIENT -> SERVER: QUIT
2020-02-03 13:39:00 SERVER -> CLIENT: 221 url-at-my-own.domain.com closing connection
2020-02-03 13:39:00 Connection: closed

现在，问题是 'obvious'，服务器要求我对自己进行身份验证，但这不是这里的问题。重要的是知道我是否真的连接到 'some-external.smtp.host' 或 'my-own.domain.com'.

上的东西

我正在与管理 'some-external.smtp.host' 的外部方打交道，该方声称我不需要进行身份验证，因为 'my-own.domain.com' 服务器 IP 已列入白名单。

他们特别声称我似乎已连接到本地 SMTP 服务器，因为第 3 行 'SERVER -> CLIENT: 220-my-own.domain.com ESMTP Exim' 中包含我自己的域名而不是他们的域名。

我相信，因为第 1 行明确指出与 'some-external.smtp.host' 建立了连接，而第 2 行指出连接已成功打开，所以第 3 行中的 220 消息是外部主机（又名 SERVER）通过名称寻址本地服务器（又名 CLIENT）。

因为我没有对服务器的管理员访问权限，所以我正在寻找方法来找出谁就在这里。我真的希望排除我没有连接到本地的东西，这真的是他们的服务器阻碍了我。

用于启动PHPMailer 的代码如下：

$mail = new PHPMailer(true);
                    try {
                        //Server settings
                        $mail->SMTPDebug = SMTP::DEBUG_CONNECTION;
                        $mail->isSMTP();
                        $mail->Host       = $this->vu['setting_mailrelay_host'];
                        if($this->vu['setting_mailrelay_username'] != '' && $this->vu['setting_mailrelay_password'] != '') {
                            $mail->SMTPAuth   = true;
                            $mail->Username   = $this->vu['setting_mailrelay_username'];
                            $mail->Password   = $this->vu['setting_mailrelay_password'];
                        }
                        $mail->SMTPSecure = $this->vu['setting_mailrelay_security'];
                        if($this->vu['setting_mailrelay_security'] == '') {
                            $mail->SMTPAutoTLS = false;
                        }
                        $mail->Port       = $this->vu['setting_mailrelay_port'];

                        //Recipients
                        $mail->setFrom($this->vu['email'], $this->vu['name']);
                        $mail->addAddress($email_to, trim($person['last_name']));
                        $mail->addReplyTo($this->vu['email'], $this->vu['name']);

                        // Content
                        $mail->isHTML(true);
                        $mail->Subject = $subject;
                        $mail->Body    = $mailBody;
                        $mail->AltBody = $message_plain;

                        $mail->send();
                        echo 'Message has been sent';
                    } catch (Exception $e) {
                        echo "Message could not be sent. Mailer Error: {$mail->ErrorInfo}";
                    }

我的SMTPAuth是假的，用户名和密码都是空的，因为外部方坚持我不需要验证。

SMTPSecure 为空且 SMTPAutoTLS 为假，因为外部方坚持认为应关闭加密。

更新： 如果我启用 TLS，日志如下：

2020-02-04 13:08:11 Connection: opening to some-external.smtp.host:25, timeout=300, options=array()
2020-02-04 13:08:11 Connection: opened
2020-02-04 13:08:11 SERVER -> CLIENT: 220-my-own.domain.com ESMTP Exim 4.92 #2 Tue, 04 Feb 2020 13:08:11 +0000 220-We do not authorize the use of this system to transport unsolicited, 220 and/or bulk e-mail.
2020-02-04 13:08:11 CLIENT -> SERVER: EHLO url-at-my-own.domain.com
2020-02-04 13:08:11 SERVER -> CLIENT: 250-my-own.domain.com Hello url-at-my-own.domain.com [31.186.175.24]250-SIZE 52428800250-8BITMIME250-PIPELINING250-AUTH PLAIN LOGIN250-STARTTLS250 HELP
2020-02-04 13:08:11 CLIENT -> SERVER: STARTTLS
2020-02-04 13:08:11 SERVER -> CLIENT: 220 TLS go ahead
2020-02-04 13:08:11 Connection failed. Error #2: stream_socket_enable_crypto(): Peer certificate CN=`my-own.domain.com' did not match expected CN=`some-external.smtp.host' [/home/tstvubo/public_html/vendor/phpmailer/phpmailer/src/SMTP.php line 429]
SMTP Error: Could not connect to SMTP host.
2020-02-04 13:08:11 CLIENT -> SERVER: QUIT
2020-02-04 13:08:12
2020-02-04 13:08:12
2020-02-04 13:08:12 Connection: closed

这会导致服务器抱怨任何一方的证书不匹配，好吧...如果我调整调用 PHP 代码以应用：

$mail->SMTPOptions = ['ssl' => [
    'verify_peer' => false,
    'verify_peer_name' => false,
    'allow_self_signed' => true
    ]
];

结果如下：

2020-02-04 13:12:51 Connection: opening to some-external.smtp.host:25, timeout=300, options=array ( 'ssl' => array ( 'verify_peer' => false, 'verify_peer_name' => false, 'allow_self_signed' => true, ),)
2020-02-04 13:12:51 Connection: opened
2020-02-04 13:12:51 SERVER -> CLIENT: 220-my-own.domain.com ESMTP Exim 4.92 #2 Tue, 04 Feb 2020 13:12:51 +0000 220-We do not authorize the use of this system to transport unsolicited, 220 and/or bulk e-mail.
2020-02-04 13:12:51 CLIENT -> SERVER: EHLO url-at-my-own.domain.com
2020-02-04 13:12:51 SERVER -> CLIENT: 250-my-own.domain.com Hello url-at-my-own.domain.com [31.186.175.24]250-SIZE 52428800250-8BITMIME250-PIPELINING250-AUTH PLAIN LOGIN250-STARTTLS250 HELP
2020-02-04 13:12:51 CLIENT -> SERVER: STARTTLS
2020-02-04 13:12:51 SERVER -> CLIENT: 220 TLS go ahead
2020-02-04 13:12:51 CLIENT -> SERVER: EHLO url-at-my-own.domain.com
2020-02-04 13:12:51 SERVER -> CLIENT: 250-my-own.domain.com Hello url-at-my-own.domain.com [31.186.175.24]250-SIZE 52428800250-8BITMIME250-PIPELINING250-AUTH PLAIN LOGIN250 HELP
2020-02-04 13:12:51 CLIENT -> SERVER: MAIL FROM:<info@domain.com>
2020-02-04 13:12:52 SERVER -> CLIENT: 250 OK
2020-02-04 13:12:52 CLIENT -> SERVER: RCPT TO:<recipient@hotmail.com>
2020-02-04 13:12:52 SERVER -> CLIENT: 550-Please turn on SMTP Authentication in your mail client. 550-(url-at-my-own.domain.com) [31.186.175.24]:36810 is not550 permitted to relay through this server without authentication.
2020-02-04 13:12:52 SMTP ERROR: RCPT TO command failed: 550-Please turn on SMTP Authentication in your mail client. 550-(url-at-my-own.domain.com) [31.186.175.24]:36810 is not550 permitted to relay through this server without authentication.
2020-02-04 13:12:52 CLIENT -> SERVER: QUIT
2020-02-04 13:12:52 SERVER -> CLIENT: 221 my-own.domain.com closing connection
2020-02-04 13:12:52 Connection: closed

现在它再次要求身份验证。

由此得出以下结论：

我肯定连接到外部 SMTP 服务器。
不管外界怎么说，简单的IP白名单是不行的。
我需要一些身份验证凭据或适当的证书才能与之通信。

判决？

Answer 1

实际阅读错误消息总是一个 非常非常好的主意，尤其是这一点：

Peer certificate CN='my-own.domain.com' did not match expected CN='some-external.smtp.host'

这意味着虽然您可能要求连接到 some-external.smtp.host（因为这是您在 Host 属性中输入的内容），但您实际上已连接到 my-own.domain.com.

这通常是由于防火墙规则重定向了 SMTP 流量 – 这也意味着 TLS 正在完全它的设计目的并提醒您您的流量实际上受到中间人攻击（通过您自己的防火墙），因此像往常一样禁用证书验证是个坏主意。 the PHPMailer troubleshooting guide.

中涵盖了这个确切的问题

所以他们说的是对的；不是他们这样做的——是您的邮件服务器在请求身份验证，而不是他们的。

PHPMailer：我是否连接到外部 SMTP？

PHPMailer: Am I connected to external SMPT or not?

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