Spammers continually send email with different subjects and offers in order to entice users to buy their products. Many of these products are; fakes and knock-offs or potentially dangerous to the purchaser. Due to the low cost of sending spam, even with the extremely low response rate, spammers can make a significant profit fairly easily. The more emails a spammer can send, the greater his profit while the cost remains nearly zero.

Spammers rarely honor opt-out requests. It's work for them to process opt-outs, sending less spam doesn't cost them any less, and who knows, you might be one of the suckers who responds next time.

Unlike direct mail or telemarketing, email spam has very low per-message cost. In many cases spammers have almost no cost because they are sending email through other people's computers that are infected with a worm or virus, which causes others to bear the cost of their messaging. As a result, despite extremely low response rates, spammers can make a profit fairly easily. The more emails a spammer can send, the greater his profit while the cost remains nearly constant.