E-mail spam, also known as "bulk e-mail" or "junk e-mail," is a subset of spam that involves nearly identical messages sent to numerous recipients by e-mail. A common synonym for spam is unsolicited bulk e-mail (UBE). Definitions of spam usually include the aspects that email is unsolicited and sent in bulk. "UCE" refers specifically to "unsolicited commercial e-mail."
E-mail spam slowly but exponentially grew for several decades to several billion messages a day. Spam has frustrated, confused, and annoyed e-mail users.