A captcha requirement would reduce it a lot, The problem is not so much that they are succeeding in their subscriptions, but that there is such a flood that merely executing the python to load the page slows the system to a crawl. Thus the sysadmins are working on cutting them off at the apache level, or similar. The requests come from thousands of ip addresses so it's not feasible to block that way.
Anyway, sysad...@fsf.org is the place to send suggestions ... best, karl
