A month or two ago, the load of junkmail intercepted for me by Pobox suddenly jumped from about one hundred pieces a day to well over two hundred. (The difference, to judge by titles, consists of repeated pleadings from alleged horny women.)
I have long been in the habit of carefully searching the spam reports for false positives, typically finding one every 3–4 days. (Each of these is a mass-mailing to which I subscribed; I don’t recall if Pobox has ever held up genuine personal mail, though Gmail did, back when that was my primary mailbox.) Now that the burden of this chore has suddenly doubled, I find myself wishing Pobox would make more errors, to reward me.
I see an analogy with the uncanny valley phenomenon, and wonder whether anyone has tried to find a psychological optimum in error rates for problems like this.
I once read somewhere that a “teaser” toy for cats should let the cat catch the “prey” one time in six.