So I get quite a lot of mail every day, like a lot of us do. But there is no way that I can read all of them at once or even start answering them. I normally filter out the really vital stuff every morning and evening and then when I get time I read the rest. When I need to answer something and I don't have the time to do this I flag the mail with a little star. Now when I get time I start answering the mails that I have put a little star on. I further use my mail as a TODO list. So I send myself a mail with what I have to do and add a star. So I end up with a list of stuff I have to answer or do. Now there is a flaw with doing it this way. Think about it. .....
Ok the problem is that GMail orders the newest message first. So you see the latest message on the top. Now when you start working of your TODO list you start with the newest item. As you never manage to answer all messages you are always left with some at the bottom. You are answering mails like a stack. Which results in that you will have mails at the bottom that are really old. And as long as you don't work of the stack to the bottom they will age continuously. So there is really important stuff in my TODO list I just forgot about and never did. I should have really just checked the dates once :)