The getting things done by David Allen is a very good system. I now use it more than 2 years.
David talks about the base of your inbox.
Everytime I read my e-mail, I will empty my e-mail inbox. My e-mail inbox base is zero. What is yours?
How many in messages do you have?
My physical inbox is not emptied everyday, that is mostly because I process my physical inbox on a weekly or bi-weekly base.