moderation

hello ! i am new to this forum and have few doubts reg. the moderation of messages. Is there any way by which the messages can be moderated ..i mean the message should get the moderators approval before it gets posted onto the forum...???The message should not get posted directly by the member instead it must go to the moderator first and once the moderator approves it should get posted. ...to prevent the junk from getting posted on the forum...