Sending multiple files in email using PHP

<?php

// array with filenames to be sent as attachment
$files = array("emi_pdf/Self_Employee_1330438553.pdf",
"emi_pdf/Self_Employee_1330439327.pdf","emi_pdf/Self_Employee_1330438611.pdf");

// email fields: to, from, subject, and so on
$to = "abc.kumar@gmail.com"; 
$from = "me@domain.com"; 
$subject = "send email with pdf attachment"; 
$message = "<p>Please see the attachment.</p>";

$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($files);$x++){
$file = fopen($files[$x],"rb");
$data = fread($file,filesize($files[$x]));
fclose($file);
$data = chunk_split(base64_encode($data));
$message .= "Content-Type: {\"application/octet-stream\"};\n" . " name=\"$files[$x]\"\n" . 
"Content-Disposition: attachment;\n" . " filename=\"$files[$x]\"\n" . 
"Content-Transfer-Encoding: base64\n\n" . $data . "\n\n";
$message .= "--{$mime_boundary}\n";
}

// send

$ok = @mail($to, $subject, $message, $headers); 
if ($ok) { 
echo "<p>mail sent to $to!</p>"; 
} else { 
echo "<p>mail could not be sent!</p>"; 
} 

?>