If one allows visitors of a WordPress blog to register themselves and post to the blog without moderation(i.e. without submit for review), malicious visitors may try to
1)Post a large number of posts and fill up the server space
2)Post a few large posts and fill up the server space
3)Create a large number of drafts and fill up the server space
4)Post inappropriate content
Does WordPress have mechanisms to prevent these? Or any plugins to do this?
P.S: If you see any other problems I have missed please point them out as well.