One mistake per day is enough for the knives to come out. On a big mailing list, think about how many 9's of accuracy you have to have to keep one incident from happening per day. Per week. Per month.

If you asked people, one per month would be a 'working' system, if you catch them on a good day. 'Never' is a very long time.

I've never seen it. I'm sure that works "in theory"