Thanks for that post. In answer to some of the suggestions and questions:

The current forum software is set up to require one of the moderators to approve new members. We catch the vast majority of spammers that way. You can set your watch by when some of them automagically do it. <sigh> The new version of the forum software will allow us to define certain problem domains and they will automagically be deleted without our intervention. That covers about 90% of them. The remaining we have to do manually. Some are obvious and we can catch. Some are more devious, using normal ISP addresses and they may get through. But, as noted in his post, if you just ignore them, we will catch them and delete them. The software we are using has only these limited tools. But, they will suffice. It could be lots worse. We can moderate posts, but right now it is all or nothing.

It is hoped that future software updates will provide more anti-spam tools, but for now at least, it's under control, if not totally eliminated. Best we can hope for at the moment.