how many electronic mails are exchanged everyday in the U.S. and in the world?

30 billions in the world eveerryday and almost half is spam

I need an exact citation and estimate, from a credible source

This is all I could find, on page 7:
http://www.pewinternet.org/pdfs/PIP_Spam_Report.pdf

Hello,

There are more than 150 Billion active email addresses in the world
today. Out of the 150 Billion addresses about 60% are in North
America.

This research is based on Arthur Anderson research results. And the
date for that research conducted was July 2004 and now chances are
that the number had grown higher.

Hope this helps

Cheers

N Bridley

thanks evilsaltine-ga but the pew study does'nt even have a footnote
or any reference as to where they got that stat from.