1982, short for electronic mail (1977; see electronic + mail (n.1)); this led to the contemptuous application of snail mail (1983) to the old system.
Even aerial navigation in 1999 was found too slow to convey and deliver the mails. The pneumatic tube system was even swifter, and with such facilities at hand it is not surprising that people in San Francisco received four daily editions of the Manhattan journals, although the distance between Sandy Hook and the Golden Gate is a matter of 3,600 miles. ["Looking Forward," Arthur Bird, 1899]
Associated Press style guide collapsed it to email 2011.