Marc -- Speaking in an official capacity as chair of the SpamAssassin PMC -- we _generally_ welcome off-topic conversations on the users list. As has been noted, some good ideas have come from them, and they're generally helpful.
However, recently, you have initiated a large number of off-topic threads that have little or nothing to do with SpamAssassin -- basically, using this list as a venue to discuss other spam-related topics. A little moderation is requested, especially when it comes to the quantities of messages posted, or the likelihood that a thread will be controversial or generate a lot of off-topic traffic. There are much more suitable venues, such as SPAM-L, or even a personal list or blog. In particular, the "SPF is hopelessly broken and must die!" thread would be *much* better off at SPAM-L or the openspf lists, and not here. In our opinion, it has reached the end of its useful life. I'd appreciate it if you could avoid perpetuating it further here. Thanks, --j.