During a keynote at the Broadband World Forum Europe 2007, Belgacom presented some figures about the number of spam.
The total was almost 27 billion estimated for this year. Three years ago this number was 'only' 1,1 billion. About 88.5 percent of all email is considered as spam.
To combat image or pdf spam, Belgacom is using an additional technique based on the reputation of the sender. To achieve this, they work together with other European Telecom Operators but not with Belgian competitors such as Telenet.
Original story from zdnet.be (in dutch).
One of the reason of the increase is the difficulty in shutting down spambots due to Fast Flux DNS. Fast-Flux Spam and Scams Increasin (Ddanchev) shows us some nice graphics that try to map out this fast rotation. Here is his original analysis about the storm worm Fast Flux Network.