How can PHP developers troubleshoot issues related to sending email attachments through contact forms?

// Example PHP code snippet to send email with attachment
$to = "recipient@example.com";
$subject = "Test Email with Attachment";
$message = "This is a test email with attachment.";

$attachment_path = "/path/to/attachment/file.pdf";
$attachment_filename = "file.pdf";

$from_email = "sender@example.com";
$from_name = "Sender Name";

$boundary = md5(uniqid(time()));

$headers = "From: $from_name <$from_email>\r\n";
$headers .= "MIME-Version: 1.0\r\n";
$headers .= "Content-Type: multipart/mixed; boundary=\"$boundary\"\r\n";

$message = "--$boundary\r\n";
$message .= "Content-Type: text/plain; charset=\"iso-8859-1\"\r\n";
$message .= "Content-Transfer-Encoding: 7bit\r\n\r\n";
$message .= $message."\r\n";

if(file_exists($attachment_path)){
    $file = file_get_contents($attachment_path);
    $message .= "--$boundary\r\n";
    $message .= "Content-Type: application/pdf; name=\"$attachment_filename\"\r\n";
    $message .= "Content-Transfer-Encoding: base64\r\n";
    $message .= "Content-Disposition: attachment; filename=\"$attachment_filename\"\r\n";
    $message .= base64_encode($file)."\r\n";
    $message .= "--$boundary--\r\n";
}

// Send the email
$mail_sent = mail($to, $subject, $message, $headers);

if($mail_sent){
    echo "Email sent successfully with attachment.";
} else {
    echo "Failed to send email with attachment.";
}