All of my forums I require that users sign up in order to post or reply. In the past I allowed guests to make posts, but eventually it told them they needed to sign up if they want access to editing their posts or use other features signed up users get. But, I eventually took the feature away, as I saw no point in allowing people to post without an account. It leaves the risk of spam and offensive content posted, so I keep it to requiring a sign-up to the site in order to post. And yet, I still have rules like they have to make a certain amount of replies before they can post.