Peter Hartzler wrote, | The original question did want limiting per sender, but that option was | dismissed as being 'probably impossible' or some such... Anyhow, I | suspect that passing the From address to an external prog which returns a | useful code, depending on recent history wouldn't be that difficult, I | shouldn't think. But it would be such an invitation to forgery. Suppose, Peter, that you and I get into a quarrel on a list. I wait until you're asleep or commuting, and I fire off a bunch of posts forged to appear as if from you, that make your position look totally ridiculous, supporting it with obvious falsehoods or laughably bad logic, and I pepper them with childish insults against me (with a lot of profanity if the list doesn't have a content filter) to embarrass you further. Then in the last one that uses up your quota for the day, Fake Pete posts an effusive apology with a complete retraction and a full agreement with my own position. Meanwhile, I'm also firing off intelligent, cogent posts (at least in my own opinion) under my own name besides the posts as Fake Pete, wasting my own quota, using my last allowed post of the day to accept (or maybe refuse) Fake Pete's apology and recantantion. You get back to your email, you see what I've pulled, and you are hopping mad. But until midnight in the listowner's time zone or manual action by the listowner clears your quota, you can't post any defense of your position; you can't post to expose me as the forger of those posts; and you can't retaliate by forging posts under my name because I've used up my own quota as well as yours. Will it catch up with me? Of course: the listowner will kick me off, ban me, and post an explanation to the membership of what really went on with an apology to them all, especially you, for setting up a system with such a big hole in it. But look at the mess in the meanwhile. Software is too easy to fool. Only a human moderator can administer a posting quota.