AFAICS, no one here, including the author, has mentioned the leading reason that users are frustrated w/ e-mail: spam. More than 90% of all e-mail traffic is spam, and it has become excruciating, not to mention quite expensive, to cut through it all with sufficient aplomb for e-mail to continue to be a useful tool.

Like fax technology before it, e-mail is not ideally suited to most of the uses to which it is put. We used it because that was the best tool available at the time. But e-mail lives in the gutter between blogs and IM, and now we have technology (like Facebook) that can bridge the two more effectively. Moreover, these other kinds of messaging technology are far more resistant to the abuse to which e-mail is structurally and tragically vulnerable.

I've been an IT professional for more than 30 years, and I'm here to remind you that IT stands still for no one; it's an ongoing revolution, and we all benefit by keeping up with it. There isn't another option.