$to = 'user@example.com';
$subject = '欢迎加入我们！';
$message = '


    


    
你好，
    
感谢您注册我们的服务。


';

$headers = "MIME-Version: 1.0" . "\r\n";
$headers .= "Content-type:text/html;charset=UTF-8" . "\r\n";
$headers .= 'From: admin@yoursite.com' . "\r\n";

mail($to, $subject, $message, $headers);

    
    


    

        
欢迎，{name}！
        
您的账号 {email} 已成功注册。
        
点击下面链接激活账户：

        激活账户
        
        
    

function sendHtmlEmail($to, $templateFile, $variables) {
    // 读取模板
    if (!file_exists($templateFile)) {
        return false;
    }
    $message = file_get_contents($templateFile);

    // 替换变量
    foreach ($variables as $key => $value) {
        $message = str_replace('{' . $key . '}', $value, $message);
    }

    // 邮件头设置
    $headers = "MIME-Version: 1.0\r\n";
    $headers .= "Content-type: text/html; charset=UTF-8\r\n";
    $headers .= "From: admin@yoursite.com\r\n";

    $subject = $variables['subject'] ?? '通知邮件';

    return mail($to, $subject, $message, $headers);
}

// 调用示例
$variables = [
    'name'            => '张三',
    'email'           => 'zhangsan@example.com',
    'activation_link' => 'https://yoursite.com/activate?token=abc123',
    'subject'         => '欢迎注册'
];

sendHtmlEmail('zhangsan@example.com', 'welcome_email.html', $variables);

use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\SMTP;

$mail = new PHPMailer(true);
try {
    $mail->isSMTP();
    $mail->Host       = 'smtp.example.com';
    $mail->SMTPAuth   = true;
    $mail->Username   = 'your@email.com';
    $mail->Password   = 'password';
    $mail->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS;
    $mail->Port       = 587;

    $mail->setFrom('admin@yoursite.com', '系统');
    $mail->addAddress($to);

    $mail->isHTML(true);
    $mail->Subject = $variables['subject'];
    $mail->Body    = $message; // 经过变量替换的HTML内容

    $mail->send();
} catch (Exception $e) {
    echo "邮件发送失败: {$mail->ErrorInfo}";
}