An estimated 247 billion emails are sent each day

"The number of worldwide email users is projected to increase from over 1.4 billion in 2009 to almost 1.9 billion by 2013. In 2009, 74% of all email accounts will belong to consumers, and 24% to corporate users.
Worldwide email traffic will total 247 billion messages per day in 2009. By 2013, this figure will almost double to 507 billion messages per day.
In 2009, about 81% of all email traffic is spam. According to our projections, a typical 1,000-user organization can spend upwards of $1.8 million a year to manage spam."
Source: Press release from The Radicati Group, 6th May 2009