A survey of 1000 workers in the USA revealed that they each receive an average of 178 email messages a day, most of which they did not consider relevant. A similar survey in the UK stated that workers claimed to spend an hour a day responding to emails which they did not consider important.
People have become obsessed with being available at all hours and in all places. Equally, they expect others to be available immediately, and over-react when they cannot contact the person they want to when they want to. They have car answering phones, workplace voice-mail, answering services, home answering phones, emails, mobile phones, fax machines. They are afraid to get rid of any of them, or to turn any of them off because they might miss an important call; they are therefore obliged to answer all the unimportant calls as well. The quantity of incoming messages becomes so great that people are incapable of prioritising them.