function uidl ($msgNum = "")
    {
        //  Returns the UIDL of the msg specified. If called with
        //  no arguments, returns an associative array where each
        //  undeleted msg num is a key, and the msg's uidl is the element
        //  Array element 0 will contain the total number of msgs

        if(!isset($this->FP)) {
            $this->ERROR = "POP3 uidl: " . _("No connection to server");
            return false;
        }

        $fp = $this->FP;
        $buffer = $this->BUFFER;

        if(!empty($msgNum)) {
            $cmd = "UIDL $msgNum";
            $reply = $this->send_cmd($cmd);
            if(!$this->is_ok($reply))
            {
                $this->ERROR = "POP3 uidl: " . _("Error ") . "[$reply]";
                return false;
            }
            list ($ok,$num,$myUidl) = preg_split('/\s+/',$reply);
            return $myUidl;
        } else {
            $this->update_timer();

            $UIDLArray = array();
            $Total = $this->COUNT;
            $UIDLArray[0] = $Total;

            if ($Total < 1)
            {
                return $UIDLArray;
            }
            $cmd = "UIDL";
            fwrite($fp, "UIDL\r\n");
            $reply = fgets($fp, $buffer);
            $reply = $this->strip_clf($reply);
            if($this->DEBUG) { @error_log("POP3 SEND [$cmd] GOT [$reply]",0); }
            if(!$this->is_ok($reply))
            {
                $this->ERROR = "POP3 uidl: " . _("Error ") . "[$reply]";
                return false;
            }

            $line = "";
            $count = 1;
            $line = fgets($fp,$buffer);
            while ( !preg_match('/^\.\r\n/',$line)) {
                list ($msg,$msgUidl) = preg_split('/\s+/',$line);
                $msgUidl = $this->strip_clf($msgUidl);
                if($count == $msg) {
                    $UIDLArray[$msg] = $msgUidl;
                }
                else
                {
                    $UIDLArray[$count] = 'deleted';
                }
                $count++;
                $line = fgets($fp,$buffer);
            }
        }
        return $UIDLArray;
    }