Why do you give out OP to random people? I would never ever give anyone at all that I don't know access to the "/stop command", because that would "kill" your server until you would be able to start it up. Get permissions and then give them a rank as Moderator. As here on Planet Minecraft Moderator moderats the sites, so we don't get any rule-breakers and stuffs like that. It should be the same in-game I think. So moderator for in-game moderation, and admin for outside of the game administration, as adding plugins, and stuffs like that. If you need any help with any plugins as permissions, send me a PM, I would be glad to help you .