Send URL attachment with PHP mail() function - php

Question

I am sending attachments by uploading through <input type="file" /> but now I want to know if we can send attachments just using URL of a file?
Like if I add <input type="url" name="file[]" /> and I need to send this as attachment not in body as inline link in message.
For now I am using this code:
HTML:
<form method="post" action="code.php" enctype="multipart/form-data">
<input type="file" name="file[]" multiple="multiiple" />
<button type="submit">Submit</button>
</form>
PHP:
<?php
foreach(array_combine($_FILES['file']['tmp_name'], $_FILES['file']['name']) as $tmp_name => $file_name ) {
$filetmp[] = $tmp_name;
$filename[] = $file_name;
}
// email fields: to, from, subject, and so on
$to = "receiver_email";
$from = "sender_email";
$subject ="My subject";
$message = "My message";
$headers = "From: $from";
// boundary
$semi_rand = md5(time());
$mime_boundary = "==Multipart_Boundary_x{$semi_rand}x";
// headers for attachment
$headers .= "\nMIME-Version: 1.0\n" . "Content-Type: multipart/mixed;\n" . " boundary=\"{$mime_boundary}\"";
// multipart boundary
$message = "This is a multi-part message in MIME format.\n\n" . "--{$mime_boundary}\n" . "Content-Type: text/plain; charset=\"iso-8859-1\"\n" . "Content-Transfer-Encoding: 7bit\n\n" . $message . "\n\n";
$message .= "--{$mime_boundary}\n";
// preparing attachments
for($x=0;$x<count($filetmp);$x++){
$file = fopen($filetmp[$x],"rb");
$data = fread($file,filesize($filetmp[$x]));
fclose($file);
$data = chunk_split(base64_encode($data));
$message .= "Content-Type: {\"application/octet-stream\"};\n" . " name=\"$filename[$x]\"\n" .
"Content-Disposition: attachment;\n" . " filename=\"$filename[$x]\"\n" .
"Content-Transfer-Encoding: base64\n\n" . $data . "\n\n";
$message .= "--{$mime_boundary}\n";
}
mail($to, $subject, $message, $headers);
?>
Thanks