关于smtp发邮件，哪位高手能帮忙看看503Error:needEHLOandAUTHfirst

if(!$fp=fsockopen($this->smtp['host'],$this->smtp['port'],$errno,$errstr)){
            $this->message[]="连接邮件服务器失败，请检查：\r\n1、服务器地址和端口是否设置正确！\r\n2、网络是否通畅！";
            return false;
        }
        if(strncmp(fgets($fp,512),'220',3)!=0){
            $this->message[]="连接邮件服务器失败，请检查：\r\n1、服务器地址和端口是否设置正确！\r\n2、网络是否通畅！";
            return false;
        }
        if($this->smtp['auth']){
            fwrite($fp,"EHLO ".$this->smtp['posthost']."\r\n");
            while($rt=strtolower(fgets($fp,512))){
                if(strpos($rt,"-")!==3 || empty($rt)){
                    break;
                }elseif(strpos($rt,"2")!==0){
                    $this->message="与服务器招呼握手时错误";
                    return false;
                }
            }
            fwrite($fp, "AUTH LOGIN\r\n");
            if(strncmp(fgets($fp,512),'334',3)!=0){
                $this->message="提示服务器要登陆验证时错误";
                return false;
            }

            fwrite($fp, base64_encode($this->smtp['user'])."\r\n");
            if(strncmp(fgets($fp,512),'334',3)!=0){
                $this->message="SMTP AUTH LOGIN 验证 用户名 错误！";
                return false;
            }
            fwrite($fp, base64_encode($this->smtp['pass'])."\r\n");
            if(strncmp(fgets($fp,512),'235',3)!=0){
                $this->message="SMTP AUTH LOGIN 验证 密码 错误！";
                return false;
            }
        } else{
            fwrite($fp, "HELO ".$this->smtp['posthost']."\r\n");
        }
        $from = $this->smtp['from'];
        $from = preg_replace("/.*\<(.+?)\>.*/", "\\1", $from);
        fwrite($fp, "MAIL FROM: <$from>\r\n");
        if(strncmp(fgets($fp,512),'250',3)!=0){
            $this->message="发信人地址错误！";
            return false;
        }
        fwrite($fp, "RCPT TO: <$toemail>\r\n");
        if(strncmp(fgets($fp,512),'250',3)!=0){
            $this->message="收信人地址错误！";
            return false;
        }
        fwrite($fp, "DATA\r\n");
        if(strncmp(fgets($fp,512),'354',3)!=0){
            $this->message="邮件数据发送失败！";
            return false;
        }
        $msg  = "Date: ".date("r")."\r\n";
        $msg .= "Subject: $send_subject\r\n";
        $msg .= "$additional\r\n";
        $msg .= "$send_message\r\n.\r\n";
        fwrite($fp, $msg);
        $lastmessage = fgets($fp, 512);
        if(substr($lastmessage, 0, 3) != 250){
            $this->message="连接邮件服务器失败，请检查：\r\n1、服务器地址和端口是否设置正确！\r\n2、网络是否通畅！";
            return false;
        }
        fwrite($fp, "QUIT\r\n");
        fclose($fp);
        return true;