Until I find a better solution (like upgrading the forum software and install a specific plugin), I'm temporarily disabling new posts for new users of which I haven't checked the profile yet and validated that they are not spam bot.
Consequence: After you register it may take up to one or two days until you can actually post in the forum. Sorry for the inconvenience. I'll try to fix the problem ASAP.
Absolutely no impact for existing users.