If your warning level gets above 50 you get muted until it gets bellow 50 again, it used to be 55 but got changed when the forum name switched. You'll lose 2 warning points per days except for the day you were muted, that day you lose no points, you lose the points at the forums 0:00. 100 is the maximum warning level and you usually only get to that if you piss off a dev. It is recommended to have some map contest or something open in order to argue for an earlier unmuting.
I know more about the mute mechanics than most mods.