Back from vacation, I started to browse my bloglines while my email client was busy downloading 2,893 messages that were sent to me in the last two weeks and found this interesting WSJ article "What does your inbox say about you?" by Jeffrey Zaslow via 43 folders.
The point is that your inbox is basically a mirror of your life and your habits and that you need to walk a middle line between these two options:
"If you keep your inbox full rather than empty, it may mean you keep your life cluttered in other ways," says psychologist Dave Greenfield, who founded the Center for Internet Behavior in West Hartford, Conn. "Do you cling to the past? Do you have a lot of unfinished business in your life?"
On the other hand, if you obsessively clean your inbox every 10 minutes, you may be so quick to move on that you miss opportunities and ignore nuances. Or your compulsion for order may be sapping your energy from other endeavors, such as your family.
The article describes various methods and approaches to managing email, with the goal of understanding your "inbox behavior" so you can better understand other areas of your life.
One book mentined is by Christina Cavanagh called "Managing Your E-Mail: Thinking Outside the Inbox" where she studied studied of office workers and how they approached their email. The article references "getting to zero inbox" technique which comes from Sally McGhee's Take Back Your Life! Using Microsoft Outlook To Get Organized and Stay Organized.
I fall somewhere inbetween. I hate having a large number of emails littering my email box, but I don't zap them too quickly. I'm a big folder maker and try to set aside some time each for email housekeeping.
I've also found that using SKYPE or IM clients are useful for "ping pong" email that can really clutter your in-box. Ping-pong email is from colleagues or folks you're working with - usually a brief flurry of back and forth messages that you don't necessarily need to keep and can clutter.
The problem I have now though is that during my vacation, I read email on my treo and now I have to download to my desktop and organize the last two weeks worth of messages.