I’ve long been a fan of the Inbox Zero philosophy. I use my “Unread Messages” smart folder as my inbox, and try to keep it at zero. I’ve managed this for several years now. The notion is that if there’s not an action that comes out of a particular email, then I mark it read and move on. If I need it for some information, it’s there for reference.
I tend to forget stuff pretty quickly, particularly when I get hundreds of email messages a day, after spam removal. So I try to go through my pending email, make a note of the actions that are required, and mark the rest read. Otherwise it just accumulates forever, and once you get behind, it becomes harder and harder to catch up.
I was about 2000 messages snowed under, this morning, but I’m all caught up now. I really need to try to keep caught up now.