By George Bilbrey
Complaint rates are a major driver of anti-spam systems. A high complaint rate (number of “this is spam” reports relative to messages in the inbox) is known to drive bad delivery rates for commercial mailers.
One of the more interesting problems that I’ve run across at Return Path is trying to figure out why complaint rates for the same IP address (or domain) vary so widely across different ISPs. Here is a scatter chart of complaint rates for ~2,500 commercial email marketing IPs across two different ISPs. In this graph 0.05 = 5% complaint rate (5 messages per 100 places in the inbox).
What is apparent is:
So what might cause the variation in complaint rates? A partial list would include:
What does this mean practically for mailers and designers of anti-spam systems?
For anti-spam systems, there may be some value for gathering complaint data from variety of sources. This would allow you to catch IPs that are behaving well locally (in your network) but not behaving well outside of your network.
For commercial mailers, there are a few key “so whats”:
What do you think?