Time wasted deleting junk e-mail costs American businesses nearly $22 billion a year, according to a new study from the University of Maryland. Related Links • Spam Cost Survey (Univ. of Maryland) A telephone-based survey of adults who use the Internet found that more than three-quarters receive spam daily. The average spam messages per day is 18.5 and the average time spent per day deleting them is 2.8 minutes. The loss in productivity is equivalent to $21.6 billion per year at average U.S. wages, according to the National Technology Readiness Survey produced by Rockbridge Associates, Inc., and the Center...