Last week, National Public Radio aired a story on my Pharma Wars series, which chronicles an epic battle between men who ran two competing cybercrime empires that used spam to pimp online pharmacy sites. As I was working with the NPR reporter on the story, I was struck by how much spam has decreased over the past couple of years.
Below is a graphic that’s based on spam data collected by Symantec‘s MessageLabs. It shows that global spam volumes fell and spiked fairly regularly, from highs of 6 trillion messages sent per month to just below 1 trillion. I produced this graph based on Symantec’s raw spam data.
Some of the points on the graph where spam volumes fall precipitously roughly coincide with major disruptive events, such as the disconnection of rogue ISPs McColo Corp. and 3FN, as well as targeted takedowns against major spam botnets, including Bredolab, Rustock and Grum. Obviously, this graph shows a correlation to those events, not a direct causation; there may well have been other events other than those mentioned that caused decreases in junk email volumes worldwide. Nevertheless, it is clear that the closure of the SpamIt affiliate program in the fall of 2010 marked the beginning of a steep and steady decline of spam volumes that persists to this day.
Of course, spam volumes are relative, depending on where you live and which providers you rely on for email and connections to the larger Internet. As I was putting together these charts, I also asked for spam data from Cloudmark, a San Francisco-based email security firm. Their data (shown in the graphs below) paint a very interesting picture of the difference in percentage of email that is spam coming from users of the top three email services: The spam percentages were Yahoo! (22%), Microsoft (11%) and Google (6%).