~50 hours per month spent on reading and answering email

I read an interesting report by McKinsey on the Social Economy this morning, but what really caught my eye was a distribution of how interaction workers (knowledge workers) spend their time – and especially the amount of time invested in reading and writing email. The following quote stands out:
“The average interaction worker spends an estimated 28 percent of the workweek managing e-mail” – McKinsey
I am not sure this is surprising to any one of us, but knowing that ~50 hours a month is being applied to the task of reading and answering email, provides for a nifty rule of thumb, if you are about to embark on a new productivity optimization initiative.