I saw this chart last week (part of Marketing Sherpa's excellent "Chart of the Week" series) and it really struck a cord with me. I get a LOT of email. Most of the time I manage them actively, using the delete key as one tool in my info stream tool-kit if I don't happen to be interested in that week's content.
But lately, I've been hitting the "unsub" button a lot more. And the main reason: no longer relevant. Seems I'm not alone.