PHP Code for Testing If an SMTP Address Exists

  /*     * function email_works ($email)     * args: $email (address to test)     * We simulate an SMTP session to the server and use the 'RCPT TO'     * to see whether the mail server will accept mail for this user.     */

    function email_works ($email) {        // get the list of mail serves for the user's host/domain name        list ($addr, $hostname) = explode ("@", $email);        if (!getmxrr ($hostname, $mailhosts))            $mailhosts = array ($hostname); // if no MX records found                                            // simply try their hostname        $test_from = "me@domain.com"; // replace w/ your address        for ($i = 0; $i < count ($mailhosts); $i++)        {            // open a connection on port 25 to the recipient's mail server            $fp = fsockopen ($mailhosts[$i], 25);            if (!$fp)                continue;            $r = fgets($fp, 1024);            // talk to the mail server            fwrite ($fp, "HELO " . $_SERVER['SERVER_NAME'] . "\r\n");            $r = fgets ($fp, 1024);            if (!eregi("^250", $r))            {                fwrite ($fp, "QUIT\r\n");                fclose ($fp);                continue;            }            fwrite ($fp, "MAIL FROM: <" . $test_from . ">\r\n");            $r = fgets ($fp, 1024);            if (!eregi("^250", $r))             {                fwrite ($fp, "QUIT\r\n");                fclose ($fp);                continue;           }            fwrite ($fp, "RCPT TO: <" . $email . ">\r\n");            $r = fgets ($fp, 1024);            if (!eregi("^250", $r))            {                fwrite ($fp, "QUIT\r\n");                fclose ($fp);                continue;            }            // if we got here, we can send email from $test_from to $mail            fwrite ($fp, "QUIT\r\n");            $r = fgets($fp, 1024);            fclose ($fp);            return true;        }        return false;    }