This is all nice and easy but I always forgot one final thing: An empty inbox. All email programs and web clients I know come with a special folder called inbox where new emails are displayed. While I have always sorted mails into folders I never fully emptied my inbox. So I never had this good feeling of accomplishing something.

But a series of posts named "Inbox Zero" over at 43 Folders made me think about my approach to answering mails. Now, I keep all my mails in my inbox until I have processed or answered them. Afterwards I move them from the inbox into a folder. For doing so I created a new "general" folder which serves as a place for all mails which do not belong to a certain category or for which it makes no sense to create a new category.
It sounds like a trivial thing to do but it can make a big difference to how you feel about your mails. I highly recommend the "Inbox Zero" campaign. It offers a lot of useful tips about organizing and processing your mails.