You may open your electronic mail and find information about how to buy medicine, cheap airline tickets, books and, of course, computers and computer products. There may also be offers for investment（投资）deals, bank loans and special holidays. However, to many computer users, this use of electronic spare to sell products has become a major problem as it makes computer communication more difficult. Many companies who want to send a great deal of advertising might use the services of a spammer. A spammer is a person or company that uses computers to send out millions of copies of