SMTP连接失败求助：参照PHPMailer排障文档后问题仍未解决

错误信息 #

Connection: opening to smtp.gmail.com:587, timeout=300, options=array()

Connection failed. Error #2: stream_socket_client(): unable to connect to smtp.gmail.com:587 (A connection attempt failed because the connected party did not respond properly after a period of time, or established connection failed because connected host has failed to respond.)

SMTP ERROR: Failed to connect to server: A connection attempt failed because the connected party did not respond properly after a period of time, or the established connection failed because the connected host failed to respond. (10060)

已参照PHPMailer官方排障文档调整，但仍报错，恳请协助解决。

相关代码 #

public function Approve1($id) 
{  
    // For database
    $data = $this->ApprovalModel->requisition_approval(array('hod'=>'submit'),$id);
    if($this->db->affected_rows() > 0)
    // PHPMailer object
    $id=$this->uri->segment(3);
    $email=$this->uri->segment(4);
    $response = false;
    $mail = new PHPMailer(); 
    // SMTP configuration
    $mail->isSMTP();
    $mail->Host = 'smtp.gmail.com'; 
    $mail->SMTPDebug = 3;
    $mail->SMTPAuth = true;
    $mail->Username = 'xyz@gmail.com';   
    $mail->Password = 'xyz';
    $mail->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS;
    $mail->Port = 587; 
    $mail->setFrom('xyz@gmail.com', 'xxx');
    $mail->addAddress($email); 
    $mail->Subject = 'hii!'; 
    $mail->isHTML(true); 
    // Email body content
    $loginlink = site_url() . 'login' . '"';
    $mailContent = <<<HEREDOC
        Dear Sir/Madam ,
        Your staff asked for Manpower Request, please click this link for your approval $loginlink
        <p>Thank you,</p>
        <p>Cladtek HRIS</p>
        HEREDOC;
    $mail->Body = $mailContent; 
    // Send email
    if(!$mail->send()){
        echo 'Message could not be sent.';
        echo 'Mailer Error: ' . $mail->ErrorInfo;
    }
    else{ 
        $this->session->set_flashdata('flash', '<div class="alert alert-success" role="alert"> Submit Succesfully!<button type="button" class="close" data-dismiss="alert" aria-label="Close"><span aria-hidden="true">&times;</span></button></div>');
        return redirect('home/manage_data');
    }
}

排查解决建议 #

• 网络连通性检查：在服务器上执行telnet smtp.gmail.com 587或curl -v smtp://smtp.gmail.com:587，确认587端口是否能正常访问。大概率是服务器防火墙/安全组封禁端口，或者运营商拦截了Gmail SMTP流量，需要对应开放端口或更换网络环境测试。
• Gmail账号配置调整：
  1. 启用账号两步验证，生成应用专用密码替换代码中的普通密码，目前Gmail已不再支持普通密码直接登录SMTP服务。
  2. 若未开启两步验证，需开启"不太安全的应用访问"（该选项已逐步被Google淘汰，优先推荐应用专用密码方案）。
• PHPMailer配置优化：
  1. 添加SSL临时跳过验证配置（生产环境不建议长期使用），排查证书问题：

     $mail->SMTPOptions = array(
         'ssl' => array(
             'verify_peer' => false,
             'verify_peer_name' => false,
             'allow_self_signed' => true
         )
     );
     

  2. 尝试切换到SSL端口465：将$mail->SMTPSecure = PHPMailer::ENCRYPTION_SMTPS;和$mail->Port = 465;替换原有TLS配置。
• 代码逻辑修复：if($this->db->affected_rows() > 0)语句缺失大括号，导致后续代码只有第一行受该条件控制，逻辑存在隐患，建议补上大括号包裹需要执行的代码块。

内容的提问来源于stack exchange，提问作者Crispy Nuts