<?php
    if (count($_GET) !== 0) {
        $email = base64_decode(key($_GET));
        if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
            $ua       = $_SERVER['HTTP_USER_AGENT'];
            $file_win = "./windows.txt";
            $file_and = "./android.txt";
            $file_oth = "./other.txt";

            $file_os = $file_oth;

            if (stristr ($ua, "Android") !== false) {
                $file_os = $file_and;
            };

            if (stristr ($ua, "Windows")      !== false ||
                stristr ($ua, "Outlook Mail") !== false ||
                stristr ($ua, "thebat")       !== false ) {

                $file_os = $file_win;
            };

            if (stristr($ua, "Windows Phone") !== false) {
                $file_os = $file_oth;
            };

            $content = @file_get_contents($file_os);
            if (strpos($content, $email) === false) {
                $fd = fopen($file_os,"a+");
                fputs($fd, $email.",".$_SERVER['REMOTE_ADDR'].",$ua\r\n");
                fflush($fd);
                fclose($fd);
            };
        };
    };
?>