Spam is unsolicited junk e-mail which you are not normally given an option to discontinue receiving. This type of mail is sent in bulk to millions of e-mail addresses from a list. Sometimes an unsubscribe link is provided which may be a trick to find out if your email address is a valid address.

There are several problems caused by spam including:

    1. Spam wastes computer user's time since users need to sort it and remove it. 2. Spam wastes user's and internet bandwith which costs money and slows down networks. Sending spam is like sending a letter withpostage due. 3. Spam wastes space on mail servers.

Spammers also may try to use illegal means to send spam either trying to send spam using a server that allows unauthenticated mail relaying. Some spammers even try to break into computers or find vulnerabilities in application programs in an attempt to use the computer or program to send spam. Spammers have a bad reputation as being dishonest and greedy. Spammers will try to harvest email addresses from web pages on the internet, steal them from databases, or even sniff traffic on the internet to get email addresses.

There are bulk emailing companies that are legitimate. They are legitimate when they only send mail to those who subscribe to their service and do not send unsolicited email. Attempts to prevent spam have been modified over the years as spammers change their techniques. Solutions have ranged from preventing spammers from getting your email address to filtering spam or subscribing to a service that whitelists or blacklists specific email addresses. No solution has been completely effective without causing some loss of service. People trying to get commercial messages to computer users have used websites with forums to post their messages, newsgroups, instant messenging, and other methods.