I've seen cheap software spam pumped over our networks many thousands of times. Nice to see that spammers have kept themselves up-to-date with the times. Not only are they spamming for Windows Vista, they are using image spam to do it.
You remarked a while ago about how difficult it is to block image spam. Most image spams seem to have large areas of white and small shapes of contrasting color. Wouldn't filtering for "mostly white image" be fairly computationally inexpensive? It's cheaper than OCR, at least, and would let photos through.
As well as that glut of brown-and-green stock spams that I got in early December. Do you think that strategy is gone, or what?
I'm not sure if filtering for mostly white images would be simple. I took a course in digital image filtering a few years ago and it's true that black/white images are much easier to filter. The problem is that as soon as spam filters started doing it, spammers would stop using that technique and start going to coloured images or shades of grey.
I'm not sure why the brown/green stock spam hast stopped, but I can voice my theories:
1. Spam filters have gotten better at stopping this stuff so spammers are regrouping.
2. Spam-bots are being shut down. Either ISPs are cleaning up their act or financial negotiations have broken down between owners of the botnets and the stock pump-and-dumpers (ie, pump-and-dumpers are having to pay too much). Either that or the botnets are getting onto a lot of blacklists.
3. It's the Christmas season and spammers are going on holidays. The stock market tends to be pretty quiet in general around this time anyways.