In fact we do have temporary (10-day) bans, and flaming doesn't often lead to a lifetime ban straight off. In one well-observed case of banning this summer, the offender (who had already attracted some attention and outrage on the Forum) made a clear flame attack in a discussion thread and received a ten-day ban; before the time was up he sent a virulent mail to an Admin, pouring abuse on Rabbit and on the Staff as a group, and so it was extended to a lifetime ban.