PHP を使用してメールを送信する

<?php
// 配置SMTP服务器
$smtp_server = 'smtp.gmail.com';
$smtp_port = 587;
$smtp_username = '你的Gmail账号';
$smtp_password = '你的Gmail密码';

// 创建SMTP客户端
$smtp_client = new SMTPClient($smtp_server, $smtp_port, $smtp_username, $smtp_password);

// 发送邮件
$smtp_client->sendMail('发件人邮箱', '收件人邮箱', '邮件标题', '邮件内容');
?>

class SMTPClient {
  private $smtp_server;
  private $smtp_port;
  private $smtp_username;
  private $smtp_password;
  private $smtp_conn;

  public function __construct($smtp_server, $smtp_port, $smtp_username, $smtp_password) {
    $this->smtp_server = $smtp_server;
    $this->smtp_port = $smtp_port;
    $this->smtp_username = $smtp_username;
    $this->smtp_password = $smtp_password;

    // 连接SMTP服务器
    $this->smtp_conn = fsockopen($this->smtp_server, $this->smtp_port, $errno, $errstr, 30);

    if (!$this->smtp_conn) {
      throw new Exception("无法连接SMTP服务器: $errstr ($errno)");
    }

    // 连接成功后发送命令
    $this->sendCommand('EHLO localhost', 250);
    $this->sendCommand("AUTH LOGIN", 334);
    $this->sendCommand(base64_encode($this->smtp_username), 334);
    $this->sendCommand(base64_encode($this->smtp_password), 235);
  }

  // 发送邮件函数
  public function sendMail($from, $to, $subject, $body) {
    // 发送邮件头部
    $this->sendCommand("MAIL FROM: <$from>", 250);
    $this->sendCommand("RCPT TO: <$to>", 250);
    $this->sendCommand("DATA", 354);

    // 发送邮件内容
    fputs($this->smtp_conn, "Subject: $subject
");
    fputs($this->smtp_conn, "From: $from
");
    fputs($this->smtp_conn, "To: $to
");
    fputs($this->smtp_conn, "
");
    fputs($this->smtp_conn, "$body
");
    fputs($this->smtp_conn, ".
");

    // 发送结束命令
    $this->sendCommand("QUIT", 221);
  }

  // 发送SMTP命令
  private function sendCommand($command, $expected_response) {
    fputs($this->smtp_conn, "$command
");

    // Read response
    while(true) {
      $response = fgets($this->smtp_conn, 4096);
      if(substr($response, 3, 1) == " ") { break; }
    }

    if((int)substr($response, 0, 3) !== $expected_response) {
      throw new Exception("SMTP命令错误: " . $response);
    }
  }

  public function __destruct() {
    fclose($this->smtp_conn);
  }
}

$smtp_client->sendMail('发件人邮箱', '收件人邮箱', '邮件标题', '邮件内容');