It appears that Barry Shein via NANOG <nanog@lists.nanog.org> said:
There's too much anecdote in these discussions.
For example are there ~20 spam operations which account for 90+% of the spam? What sort of products do the major spammers spam?
Wild guess, but I suspect it's something like that, a small set of spammers accounting for most of it and then a rapidly descending long tail.
I go to conferences where we talk about questions like this. There is a complicated crime economy where different groups specialize in different things, of which sending the spam is only one bit. Believe it or not there is a lot of law enforcement action, they take these groups down all the time, but there are many of them, and they are often in countries where the government doesn't care. As an egregious example, the romance scams are mostly along the Cambodia-Burma border with people from other countries lured by promises of fake tech jobs who then can't leave. I think it is safe to say there are a lot more than 20 groups, and they're not the same groups from one year to the next. Adding to the excitement, you can send spam in lots of different ways. There was a Chinese group that specialized in iMessage and RCS spam of "you have an unpaid turnpike toll" or "you have a postage due package", directing you to very plausible fake websites where they steal your credit card info. They got busted due to poor opsec but they seem to have regrouped elsewhere in China. R's, John