What is "spam"?
Spam is a generic term for unsolicited commercial email, usually sent to
a large number of addresses at one time. Spam is undesirable because:
sendmail provides a number of facilities and defaults to
facilitate spam prevention.
- Most people don't like receiving unsolicited advertisements mixed in
with their normal email.
- Spammers often relay a few messages addressed to hundreds or
thousands of people through someone else's mail server, as shown
below. The mail server they use then bears the brunt of the work,
which uses up bandwidth and slows down the machine for legitimate