A group of California university researchers published a study on spam conversion rates. They found that, yes, there are people who buy products from spam ads. But they also found that the potential profit from a successful campaign may not be nearly as high as some pundits have speculated. The researchers set up processes for the illegal sale of pharmaceuticals and the download of malware, creating errors at the very end of the process so that no final sales could be completed and no malware was actually distributed. They estimate that a pharmaceutical spammer using the full bandwidth of the Storm botnet for a single campaign might hope to make between $7,000 and $9,500 per day.”]
Source: https://www.darkreading.com/attacks-breaches/spam-campaigns-work-but-don-t-generate-big-profits