Japanese customers more likely to send email than text on mobile phone according to comscore study"

"Europeans displaying the strongest use of text messaging with 81.7 percent sending a text message in June, compared to 66.8 percent in the U.S. and just 40.1 percent in Japan. Japanese users exhibited the highest reach in the email category at 54 percent, while consumers in the U.S. were most likely to use instant messaging services on their mobile (17.2 percent). "

Source: Japan Mobile Audience “Most Connected” with 3 of 4 Users Accessing Mobile Media in June
Comscore
October 7, 2010
http://www.comscore.com/Press_Events/Press_Releases/2010/10/comScore_Release_First_Comparative_Report_on_Mobile_Usage_in_Japan_United_States_and_Europe