Analysis of spam volume since the McColo Corp affair

In order to understand the real impact on the volume of emails filtered via our platforms and the overall spam rate for all our customers, we have carried out a daily analysis of the number of emails and the percentage of spam received since November^1st.

As our customers are businesses, the number of legitimate emails is much lower on weekends, so the spam rate increases significantly on weekends. To ensure that this analysis is not too disrupted by this finding, we have smoothed all the figures over a full week. For example, the smoothed spam rate peak is exactly 90% on November 2, whereas in reality a peak of 95.19% was reached on Sunday November 9, 2008.

In the McColo Corp* case, between November 11 and 12 2008, the spam rate dropped from 91.81% to 74.13%. Over the same period, the volume of e-mails received on our platforms fell by 36%. In the days that followed, the graphs below clearly show a drop in the spam rate and the number of emails received. This decline stopped around November 20, 2008, and began to rise again around November 27-28, 2008.

Conversely, and contrary to what some people claim, we did not experience a significant increase in the number of viruses sent after November 11, 2008. With the exception of a slight peak of 0.65% on November 14 (not significant, there are regular peaks of close to 1%), the average number of viruses received remains between 0.1 and 0.3%.

Today, we’re seeing an increase in the spam rate, but traffic is still well below the pre-November 11th volume. With the end-of-year festivities, and given the trend of the curves, it should soon reach record levels.

(*) McColo Corp is an American hosting company whose Internet access was cut off following suspicions that it was running a botnet and sending out massive amounts of spam.