Sorry, but I'm going to go into rant mode here, mostly because I don't like MrMacPlus' response. It is indicative, in my mind, of a phenomena that I refer to as anti-spam fascism. It is an attitude where the ends justify the means. An attitude that encourages authoritarian responses, since those harmed often have no say in the matter.
Many of these authoritarian responses are technical in nature. The problem with technical solutions is that they don't address the real problem, so the problem persists. It may pop up in a different form, or it may temporarily move on to easier pickings, but it will always return. Which is why these technical solutions leads to even more authoritarian technical solutions. Unfortunately the increasingly authoritarian solutions often harm innocent bystanders.
The problem of spam is actually a social issue, and it requires social solutions. Now I'm not going to blame the maintainers of these forums for ignoring those solutions, because it is clearly beyond their means. They are stuck with patching up a system that clearly barely works. But I am going to criticize people who think that these are an acceptable solutions, even when they cause harm, because that precludes the search for more effective solutions. In many respects, it only makes matters worse.
I mean, look at MrMacPlus' suggestion: the bystander should use a proxy. Not only is it inconveniencing the bystander and opening that bystander to other potential sources of harm (such as revealing their login credentials to a third party), but it is also a means for spammers to circumvent the IP address check. So nothing has really been solved. Though some things have been made worse.
