Spam is flooding the Internet with many copies of the same message, in an attempt to force the message on people who would not otherwise choose to receive it. Most spam is commercial advertising, often for dubious products, get-rich-quick schemes, or quasi-legal services. Spam costs the sender very little to send -- most of the costs are paid for by the recipient or the carriers rather than by the sender.

 

Email spam targets individual users with direct mail messages. Email spam lists are often created by scanning Usenet postings, stealing Internet mailing lists, or searching the Web for addresses.

 

Replying to spam, or even following the sender's instructions for "removal," may actually increase the amount of spam you get in the long run. By letting the spammer know that you've received the message, even though you are expressing disapproval at receiving it, you are confirming for them that your e-mail address is valid and that you read messages sent to that address. Unfortunately, many spammers do track which addresses write them back (regardless of the content of the reply) and use this information to update their mailing lists. Some even then turn around and sell these lists to other spammers.