How to avoid unwanted email

U nwanted communication ranges from nuisance (junk mail) to annoyance (telemarketing) to dangerous to the very medium conveying the message (junk fax, obscene or harassing telephone calls). The usefulness of email is seriously threatened by the commercialization of the Internet because it is easier than ever to collect address lists and cheaper than ever to mass-distribute messages. If companies spent as much money sending junk email as they do sending junk physical mail, an established Internet user would likely get more than 100 junk messages per day. Every time a user sends a message to a public newsgroup or list, fills out a Web form, or mails in a product registration card, the server cheaply obtains an email address and usually some indication of the user's interests. This information is then sold to marketing firms that easily automate mass emailings of advertisements , surveys, and other annoyances that cost the user connect time and, worse, valuable attention. More sinister unwanted email is becoming common as well, including harassing and hate mail. The main technique today for avoiding unwanted communication is to restrict the set of people to whom users give their addresses. For example, people pay to avoid having their phone numbers listed; in email, people sometimes maintain multiple email accounts, using different accounts for different purposes , such as commercial vs. personal. This unlisted address approach is expensive and slow to recover from security breaches; if an address is leaked to an adversary, the only alternative is to pay the service provider to change it (often a lengthy process). Once Despite looking like conventional email, a channelized email address and its related agent allow email users to reliably cut off unwanted correspondents.