关于olympic airlines机票的Reconfirmation

我在奥林匹亚航空公司订了2张票，在他给我发的邮件的Important Notices中有这么一条：


8.Reconfirmation You must reconfirm onward or return reservations at least 72 hours before departure of your flight. If you fail to reconfirm your reservation/s/ may be automatically cancelled.


这是什么意思啊？需要我reconfirm么，该怎么办理呢？