A recent study "Hidden Cost of Information Work: A Progress Report" conducted by IDC states that knowledge workers on average spend 13 hours per week on e-mail. Assuming average salaries this corresponds to about USD 21,000 per year. That's an interesting number!
E-mail is an important and often efficient tool, but it's worthwhile checking whether there are inefficiencies to drive out or more appropriate tools available for certain tasks.
E.g.: our experience shows that a so called CYA-culture ("cover your ass") leads to far too many CC-messages, easily doubling the number of e-mails each individual has to deal with.

Does your organisation's culture support effective and efficient use of modern communication and collaboration tools?