From the August edition of Training&Development:

"If you've become averse to picking up the phone, you're not alone. An onnline survey from META Group polled 387 U.S. Organizations to find that 80 percent of businesspeople prefer email for work-related communication. The reasons for preferring emailover the phone include:
response flexibility - 84 percent
easy communication with multiple parties - 83 percent
paper trail - 78 percent
faster communication - 40 percent
more productive - 29 percent
easier global communications - 25 percent
proper context - 24 percent

And what of the humble fax? The META Group study found that the number of faxed pages dropped 50 percent in the past five years."

But what about my favorite reason for work e-mails: I really don't want to deal with you at all and e-mail is the least heinous way to do that - 100 percent!