Most of these messages are a form of commercial advertising. These lists are bought by spammers. Your address also may be obtained by spammers who scan Usenet postings stealing Internet mailing lists, or spammers may simply search the Web for addresses. Another way you may end up on a list is when you make a connection to a Web site server. These addresses are then added to a list of people who, based on interests in that particular site, have similar tastes.
Spammers then send e-mails to addresses based on the interests of the users .
Spam costs the spammer very little to send. As a matter of fact, the cost is actually placed on the recipient or the carrier, rather than the sender. It costs the user time and money to discard these unwanted messages. ISPs and online services bear the cost of transmitting spam to their users and these costs can be passed on to the subscribers in their fees. Your request may be successful, however, your message may also be returned to you as undeliverable or your response can generate a new solicitation.