If you’ve ever wondered which ISPs are the worst at shipping spam – and how much of an issue botnets are - then here is one estimate of the problem, courtesy of Trend Micro’s Network Repuation Services.

The latest hourly figures might confirm some prejudices. The top twelve (it sounds better than ten) consist of:

1. Chinanet (China)
2. Telefonica (Spain)
3. CNC Group (China)
4. TPNet (Poland)
5. Korea Telecom (Korea)
6. Verizon (US)
7. TTnet (Turkey)
8. France Telecom (France)
9. Proxad AS (France)
10. Bezeq (Israel)
11. Telecom Italia (Italy)
12. Hanaro Telecom (Korea)

The list extends to 100, with some names form the UK making it into the statistics, with BT at 26, and Telewest at number 47, for instance. China, Spain (a proxy for Brazil) and Eastern Europe are consistently up there with the worst of them which fits in with the common notion that these countries are spam hot-spots.

And botnets? Most spam is now sent by these, networks that can control tens of thousands of ordinary PCs s a way of increasing traffic and hiding a spammer’s identity. The figures offered by Trend are only the hourly percentage change (plus/minus) rather than the more useful absolute percentage of traffic from each ISP, but they make interesting reading nonetheless.

Trend gives an explanation of how these figures are arrived at here. The calculation is not uncontentious, but there is something about the general gist of them that convinces me they are not completely fanciful.

Many thanks to Geoff Bennet of Streamshield for pointing this one out to me.