I’m sure we’ve all seen estimates of the ratio of “good” email to spam. What I offer today is a set of data points from George Mason University.
In December of 2004 (when our first spam filter was introduced) our mail server received 1.9 million “good” email messages (good defined only as making it through the spam filter—you have to assume some percentage of that was really clever spam) and 5.6 million spam messages (including, no doubt, a few false positives). Expressed in percentages, 26% of the mail we received was legitimate.
Fast forward to May, 2007 the percentage of “good” email has fallen to a mere 7% of received messages (8 million good messages and 100.2 million spam).
Here are the statistics since December 2004:
Quite a spike in spamming during April and May 2007. Will know in a few months whether it was just a “spam storm” or actually the beginning of the final deluge. Without knowing that, I think it is still easy and safe to say that we’re approaching the point where receiving any email that isn’t spam will be a statistically significant event.