As others have said, forum registration is disabled outright so that prevents that avenue for spam. We do allow guests to post, but we require them to type "RBW" somewhere in their post. This blocks automated spam yet to me is more friendly than a CAPTCHA. Registration on the main website is protected via a security key (essentially a password) which the guildmate sponsor gives to the potential new member in order for him to register. This prevents automated spam registrations on the website, and also kind of ensures that new members are recruited by somebody rather than just jumping in as total strangers.