The original function of email was for a few scientists to send text notes to each other. Now we use it to send multi-megabyte documents and evil robots spew out billions of email advertisements. I’ve seen first-hand, at a number of client sites, how badly overwhelmed the basic structure of email is. It’s so easy to send an email, and just as easy to send that email to a dozen people as to one (to make sure it doesn’t get missed!) that even small companies can easily generate thousands of emails per day.
It can’t last. The people plugged into those email systems simply can’t keep up with the flood. Forward-looking organizations are going to start looking at alternatives.
Prediction: At some point in the not terribly distant future (five or ten years?), internal email systems (within an organization) will change to look more like discussion forums or social networking sites. The current email structure will mainly serve to move emails between these systems, a background conduit rather than something that users are constantly plugged into and ruled by.