вопрос по функции отправки почты

Ниже приведенная функция не отправляет письма с вложениями файла > 4Kb. Подскажите, в чем ошибка?


<?php
function socketmail($server, $to, $from, $subject, $message, $filename, $filetype, $uploadfile) {
$connect = fsockopen ($server, 25, $errno, $errstr, 3000);
fputs($connect, "HELO localhost\n");
fputs($connect, "MAIL FROM: $from\n");
fputs($connect, "RCPT TO: $to\n");
fputs($connect, "DATA\n");
fputs($connect, "To: $to\n");
fputs($connect, "Subject: $subject\n");
fputs($connect, "MIME-Version: 1.0\n");
fputs($connect, "Content-Type: multipart/mixed; boundary=\"boundary-main\"\n\n");
fputs($connect, "--boundary-main\n");
fputs($connect, "Content-Type: text/plain; charset=UTF-8\n");
fputs($connect, "Content-Transfer-Encoding: 7bit\n");
fputs($connect, "\n");
fputs($connect, stripslashes($message)."\n\n");
fputs($connect,"\n--boundary-main\n");
if(isset($uploadfile))
{
$fd = fopen($uploadfile,"rb");
if(!$fd)
{
print("Файл $filename не может быть прочитан");
}
$filebody = fread($fd,filesize($uploadfile));
fclose($fd);
fputs($connect,"Content-Type: ".$filetype."; name=\"".$filename."\"\n");
fputs($connect,"Content-Transfer-Encoding: base64\n");
fputs($connect,"Content-Disposition: attachment; filename = \"".$filename."\"\n\n");
fwrite($connect,chunk_split(base64_encode($filebody)));
fputs($connect,"\n--boundary-main--\n.\n");
flush();
}
fputs($connect, "QUIT\n");
socket_close($connect);
}
?>

Спасибо.