A spambot is a program designed to collect, or harvest, e-mail addresses from the Internet in order to build mailing lists for sending unsolicited e-mail, also known as spam. A spambot can gather e-mail addresses from Web sites, newsgroups, special-interest group (SIG) postings, and chat-room conversations. Because e-mail addresses have a distinctive format, spambots are easy to write.
A number of legislators in the U.S. are reported to be devising laws that would outlaw the spambot. A number of programs and approaches have been devised to foil spambots. One such technique is known as munging, in which an e-mail address is deliberately modified so that a human reader can decode it but a spambot cannot. This has led to the evolution of sophisticated spambots that can recover e-mail addresses from character strings that appear to be munged.
The term spambot is sometimes used in reference to a program designed to prevent spam from reaching the subscribers of an Internet service provider (ISP). Such programs are more often called e-mail blockers or filters. Occasionally, such a blocker may inadvertently prevent a legitimate e-mail message from reaching a subscriber. This can be prevented by allowing each subscriber to generate a whitelist, or a list of specific e-mail addresses the blocker should let pass.