How can PHP beginners properly install and use PHPMailer for sending emails with attachments without using SMTP or signing up for an email service?

PHP beginners can use PHPMailer to send emails with attachments without using SMTP or signing up for an email service by setting the `isMail()` method in PHPMailer. This method allows PHPMailer to send emails using the local mail transfer agent (MTA) configured on the server. Below is a code snippet demonstrating how to use PHPMailer to send emails with attachments using the `isMail()` method:

<?php
// Include PHPMailer autoload file
require 'path/to/PHPMailerAutoload.php';

// Create a new PHPMailer instance
$mail = new PHPMailer;

// Set the mailer to use the mail() function
$mail->isMail();

// Set the recipient email address
$mail->addAddress('recipient@example.com');

// Set the sender email address
$mail->setFrom('sender@example.com', 'Sender Name');

// Set email subject
$mail->Subject = 'Test Email with Attachment';

// Set email body
$mail->Body = 'This is a test email with attachment.';

// Add attachment
$mail->addAttachment('path/to/attachment.pdf');

// Send the email
if(!$mail->send()) {
    echo 'Email could not be sent.';
    echo 'Mailer Error: ' . $mail->ErrorInfo;
} else {
    echo 'Email sent successfully!';
}
?>