<?php

/* connect to gmail */
$hostname = '{imap.gmail.com:993/imap/ssl/novalidate-cert}INBOX';
$username = '##YOUR EMAIL ID';
$password = '##YOUR PASSWORD';

/* try to connect */
$inbox = imap_open($hostname, $username, $password) or die('Cannot connect to Gmail: ' . imap_last_error());
$emails = imap_search($inbox, 'SUBJECT "##EMAIL SUBJECT"');
foreach ($emails as $email_msg) {
    $structure = imap_fetchstructure($inbox, $email_msg);
    $msg_info = imap_headerinfo($inbox, $email_msg);
    if (isset($structure->parts) && empty($structure->parts) == FALSE) {
        foreach ($structure->parts as $key => $part_info) {

            if (isset($part_info->disposition) && $part_info->disposition == 'ATTACHMENT' && count($part_info->dparameters) > 0) {
                foreach ($part_info->dparameters as $file) {
                    if ($file->attribute == 'FILENAME') {

                        $file_info = pathinfo($file->value);
                        $fp = fopen('files/' . $msg_info->subject . '.' . $file_info['extension'], 'w+') or exit('Failed to open file');
                        $msg_body = imap_fetchbody($inbox, $email_msg, $key + 1);
                        $content = base64_decode($msg_body);
                        fwrite($fp, $content);
                    }
                }
            }
        }
    }
}
?>