Spam is the common term (used a noun and a verb) used for unsolicited e-mail.  Although generally sent out in bulk, this criteria is not necessary for unsolicited e-mail to be considered "spam".

Most ISPs (Internet Service Providers) include the right to discontinue your service if you spam; the same is true for web based e-mail services.  If you mention your website in a spam e-mail, the server hosting your site may have the right to discontinue that service.

Spam is very similar to the unsolicited telephone calls you probably receive constantly, trying to get you to try a new credit card or a home service.  For a variety of reasons, however, people are reacting to e-mail spam strongly, with governmental regulations already passed in some states, and being considered in others.

Although not as tightly regulated, sending a single message to multiple newsgroups at the same time is considered spamming as well.  Newsgroup users become very offended by this type of spam.

Be aware that the minute you post an e-mail address on virtually any public newsgroup or classified ad, you will be targeted for great quantities of spam.  There are still ways some people get around it, although if you request (politely is suggested) to be removed from a mailing list, that request is generally honored.

For the record, I feel there is a considerable difference between target marketing and spam; however, this difference is not recognized by authorities, ISPs or e-mail providers.

To protect your Internet service, your website location, and your reputation, I strongly urge you not to participate in bulk e-mail if unsolicited.

*** Very Important ***

People who subscribe to newsletters, or request information are considered to have "opted-in" (exercised the option to receive specific mail).  Receiving the requested e-mail from an  "opt-in" lists is not considered spam.  Many newsletters or e-zines (electronic magazines) sell advertisements.