Thanks for your reply. I guess this solution is quite good for a start. But if I understand correctly, the spam-filter trashes the comment after the user has written it, right? Seems quite unfair to me. Isn't there any way to completly disable the comment box for a group?

Hello everyone.
A few days ago I switched my website to s9y. To restrict the comment function I found and installed the user self-registration plugin. The user is put into a group "User" which has no rights (i.e. all checkboxes are unchecked in this group) and the user is disabled. However the user ...