PHP发送带有附件和变量值的松散消息

<?php
$to = "recipient@example.com";
$subject = "松散消息";
$message = "这是一条带有附件和变量值的松散消息。";
$from = "sender@example.com";

// 构建邮件头部
$headers = "From: $from\r\n";
$headers .= "MIME-Version: 1.0\r\n";
$headers .= "Content-Type: multipart/mixed; boundary=\"boundary\"\r\n";

// 构建邮件内容
$body = "--boundary\r\n";
$body .= "Content-Type: text/plain; charset=\"utf-8\"\r\n";
$body .= "Content-Transfer-Encoding: 7bit\r\n\r\n";
$body .= $message."\r\n\r\n";

// 添加附件
$attachment = "path/to/attachment.pdf";
$file = fopen($attachment, "r");
$data = fread($file, filesize($attachment));
fclose($file);
$data = chunk_split(base64_encode($data));
$body .= "--boundary\r\n";
$body .= "Content-Type: application/pdf; name=\"attachment.pdf\"\r\n";
$body .= "Content-Transfer-Encoding: base64\r\n";
$body .= "Content-Disposition: attachment\r\n\r\n";
$body .= $data."\r\n\r\n";
$body .= "--boundary--";

// 发送邮件
if (mail($to, $subject, $body, $headers)) {
    echo "邮件发送成功！";
} else {
    echo "邮件发送失败！";
}
?>