We do moderation, short-term ban (1-2 weeks), long-term ban (1-2 years), and perma ban. Short-term ban is for people who know the rules but got too comfortable; works well. And long-term bans - after a while it gets hard to separate who really shouldn't be allowed back ever again and who could be given another chance years later. Someone emails, and I don't remember what the issue was. 20 posts on account, banned 7 years ago by a mod long gone, for "harassing members." What was the story, was it a troll or an aspie looking for friends? So we started doing 1-2 year bans for those who could be allowed back.