In various places on talosintelligence.com, email volume statistics are shown (such as on the home page map, the Reputation Details section of an IP address lookup, etc.). This is how we determine these numbers.
Similar to the Richter scale used to measure earthquakes, the Talos Reputation Center volume magnitude is a measure of message volume calculated using a log scale with a base of 10. The maximum theoretical value of the scale is set to 10, which equates to 100% of the world’s email message volume. Using our log scale, a one point decrease in magnitude equates to a 10x decrease in actual volume.
For example, with a world wide daily volume of 200 billion messages/day a domain with a volume magnitude of 5 would have an estimated volume of 2,000,000/day while a sender with a volume magnitude of 6 would have an estimated daily volume of 20,000,000/day.
The following table illustrates the percentage of Internet email associated with each volume magnitude: