Business emails have begun to include messages like: "Save trees; print only when necessary" and "Be cool, consider the environment; please don't print this e-mail unless you really need to." Environmentalists say "don't print" messages have merit. Despite predictions of a paperless office, according to GreenPrint Technologies Americans use enough paper every year [850 million trees worth] to build a wall 10-feet-high stretching from New York to Tokyo and beyond. [According to ncenvirothon.org, Americans use enough paper and wood products each year to fill a train of two million boxcars circling the Earth at the equator.]