I am curious if there is anyway to ban some one without the admin on. I just spent aobut 5 hours buling a tower. and the admins had logged on an hour or two before I finished. A played named 'tytens' came on and destroyed everything withing 15 min. I tried to rebuild but he would destroy the bottom from under me.
With no admin or OP on, a server without voteban has no means for an ordinary player to ban a griefer. Unfortunately, it falls to the administration to either monitor the server constantly or build a prison at spawn to stop newcomers while they're away.