Fernando gives some more commentary on how technology has failed us in the area of email:
Some of us have been doing a bit of work on tools for helping manage email. Just a beginning. I totally agree that dropping any email that needs more than 2 minutes to respond is filtering all worthwhile thought from your exchanges, maybe from your day. What I would like is a convenient way to slow down email, especially the kind of email that doesn't need much thought. For example, I'd like an adaptive delay for my outgoing replies. If an outgoing reply is delayed by 8 hours, the reply to the reply will arrive tomorrow. Of course, some replies I want to go out right away. that's why intelligence and adaptation are needed for this purpose.
In addition, I think that one of the big problems with email is there is no direct relationship between the time stamp on an email and when the sender expects or requires a reply. This can be inferred in part by various priority settings, but these are easy to ignore and often mean different things to different people (an ontological commitment problem if ever there was one!). Perhaps analysis of the content as well as past interactions with the sender could be used to provide a better sorting function...