在php中发送带附件的电子邮件,而不将文件保存到webserver

<?php
$to = "recipient@example.com";
$subject = "Test email with attachment";
$message = "This is a test email with attachment.";
$headers = "From: sender@example.com";

// Define the attachment
$file_name = "example.pdf";
$file_path = "/path/to/example.pdf";
$file_type = "application/pdf";
$file_contents = file_get_contents($file_path);
$attachment = chunk_split(base64_encode($file_contents));

// Set the headers for the attachment
$headers .= "\nMIME-Version: 1.0";
$headers .= "\nContent-Type: multipart/mixed; boundary=\"boundary\"";
$headers .= "\nContent-Disposition: inline";
$headers .= "\n--boundary";
$headers .= "\nContent-Type: text/plain; charset=ISO-8859-1";
$headers .= "\nContent-Transfer-Encoding: 7bit";
$headers .= "\n\n" . $message;
$headers .= "\n\n--boundary";
$headers .= "\nContent-Type: " . $file_type . "; name=\"" . $file_name . "\"";
$headers .= "\nContent-Disposition: attachment; filename=\"" . $file_name . "\"";
$headers .= "\nContent-Transfer-Encoding: base64";
$headers .= "\nX-Attachment-Id: " . rand(1000, 99999);
$headers .= "\n\n" . $attachment;
$headers .= "\n--boundary--";

// Send the email
if (mail($to, $subject, "", $headers)) {
    echo "Email sent successfully!";
} else {
    echo "Error sending email.";
}
?>

<?php
require 'PHPMailer/PHPMailer.php';
require 'PHPMailer/SMTP.php';
require 'PHPMailer/Exception.php';

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

$mail = new PHPMailer(true);

try {
    // Server settings
    $mail->SMTPDebug = SMTP::DEBUG_SERVER;
    $mail->isSMTP();
    $mail->Host = 'smtp.example.com';
    $mail->SMTPAuth = true;
    $mail->Username = 'username';
    $mail->Password = 'password';
    $mail->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS;
    $mail->Port = 587;

    // Recipients
    $mail->setFrom('sender@example.com', 'Sender Name');
    $mail->addAddress('recipient@example.com', 'Recipient Name');

    // Attachment
    $mail->addAttachment('/path/to/example.pdf', 'example.pdf');

    // Content
    $mail->isHTML(true);
    $mail->Subject = 'Test email with attachment';
    $mail->Body = 'This is a test email with attachment.';

    // Send the email
    $mail->send();
    echo 'Email sent successfully!';
} catch (Exception $e) {
    echo "Error sending email: {$mail->ErrorInfo}";
}
?>