An interesting thread circulating the internet over the past few months has been about how a significant chunk of spam stopped once a colo was shut down. What was also interesting, and equally predictable, was how the email started back up again over time.
The economics of spam is interesting. Spammers will move to the email delivery source that will provide them with the most profit, regardless of the "externalities" of this decision. So, it's not surprising that a cluster of spammers were spamming from one colo ("McColo").
Ultimately, shutting down a major spam friendly colo makes the costs to the spammers go up (at least in the short term) as they find less attractive solutions. The only way to truely stop spam (the truely unsolicited email) is to make the economics of it unattractive. A combination of really good spam filters, expensive delivery costs, and low user participation (the liklihood someone will click on the email) will cause this to happen. However, spam filters are pretty good these days, delivery costs are going up in the U.S., and user participation is not going to change that much over time. This ultimately pushes spammers offshore, which lowers deliverability, as email from outside the U.S. is trusted less by spam filters. All of these actions increase the costs to spam. This means that to equal things back out, other costs need to be lowered. Examples of this include sending out high volumes of email, without any focus on deliverability. By the sheer number of emails delivered, some will get through the filters. This creates an extremely "dirty" email, as it has no personalization. I don't know if you've noticed, but spam, which has largely been moved offshore, has gotten "dirtier" over time.
One solution many have turned to is "opt-in" spam. Effectively, email marketers get people to sign up for their emails. However, in my opinion, permission to send me email doesn't mean you can send me several emails a day about whatever you want. In some cases, I've seen marketers (in this case, I'll go so far as to say spammers) send out ten's of emails a day. That really adds up. This loophole in the CANSPAM law is a bit of a problem, but closing it creates problems for big business, which is bad. Some additional thought around legislation should be considered.
Ryan Pitylak is an anti-spam activist.