PHP: Sending email with attachments

$HTML = 'THIS IS MY MESSAGE';
$text = strip_tags($HTML);
$fromEmailName = 'My Company';
$fromEmail = 'me@mycompany.com';
$to = 'test@test.com';
$bcc = 'me@mycompany.com';
$subject = 'This is the subject';
$tmpFilename = '/tmp/dfdgdf123';
$attachFilename = 'spring_chicken.jpg';

$attachType = mime_content_type($tmpFilename);
$random_hash = md5(date('r', time()));
$headers = "From: ".$fromEmail."\r\nReply-To: ".$fromEmail;
//add boundary string and mime type specification
$headers .= "\r\nContent-Type: multipart/mixed; boundary=\"PHP-mixed-".$random_hash."\"";
//read the atachment file contents into a string,
//encode it with MIME base64,
//and split it into smaller chunks
$attachment = chunk_split(base64_encode(file_get_contents($tmpFilename)));
//define the body of the message.
ob_start(); //Turn on output buffering
?>
--PHP-mixed-<?php echo $random_hash; ?>
Content-Type: multipart/alternative; boundary="PHP-alt-<?php echo $random_hash; ?>"

--PHP-alt-<?php echo $random_hash; ?>
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: 7bit

<?php echo $text; ?>

--PHP-alt-<?php echo $random_hash; ?>
Content-Type: text/html; charset="iso-8859-1"
Content-Transfer-Encoding: 7bit

<?php echo $HTML; ?>

--PHP-alt-<?php echo $random_hash; ?>--

--PHP-mixed-<?php echo $random_hash; ?>
Content-Type: <?php echo $attachType;?>; name="<?php echo basename($attachFilename);?>"
Content-Transfer-Encoding: base64
Content-Disposition: attachment

<?php echo $attachment; ?>
--PHP-mixed-<?php echo $random_hash; ?>--

<?php
//copy current buffer contents into $message variable and delete current output buffer
$message = ob_get_clean();
//send the email
$mail_sent = @mail( $to, $subject, $message, $headers );
?>