Tom Cochran in his HBR article E-mail is not free talks about the financial cost of information overload in organizations through e-mail overflow. They actually conducted a study to figure out the average time spent on managing the e-mail flow, in responding to the e-mails and average response size. The time when converted into figures sounds huge.
A large part of wastage comes from a tendency to copy or blind copy people whom you want to know about the work or a particular communication. I agree to a large extent with Tom that just because it is so easy to shoot an e-mail, we just have too many in out inbox and outbox, we do not realize the time required to read and answer them. However there is one point that I disagree on – there is a statistic on e-mails that come with documents for review, specially to senior management team. Now it can be safely assumed that with or without e-mail these documents would have come to the required people and asked for the attention they need. A lot of offline / paper communication has shifted to e-mail and hence they look overflowing sometime, and we forget that the release time elsewhere, like printing, someone actually walking up to your cabin and delivering it, or a courier service if you are not co-located.
Having said that I guess e-mail optimization will happen over a period of time. It is like when mobile phones first came and when incoming calls became free in India, people used to be talking on the phone constantly – just realizing the new power in their hands, but as they realized the time lost due to this and the fact that this power in their hands is there to stay, the optimal behavior came forth. I see that happening to e-mails as well, forwarded e-mails have gone down drastically, marketing e-mails continue but the spam filters are improving, people are getting more professional and they write to-the-point e-mails.
So, next time you send an e-mail, remember there is a cost associated with it though it seems free to us.