Synonymous with Impersonation, Masquerading or Spoofing. Offensive screensavers is the downloading of offensive graphics from websites to use as screensavers. PornNet is the accessing of pornographic websites during work time. Normal postal mail, where an actual physical letter or package is delivered. Electronic junk mail or junk newsgroup postings.
Some people define spam even more generally as any unsolicited e-mail.
Spam is generally e-mail advertising for some product sent to a mailing list or newsgroup.