Counter point. If this(free postage) is an easy and good proxy for detecting this type of scam. By doing this they might stop(doing free postage) . And then you and others lose their easy no effor detection?
'Oh gosh, wait a moment, I just realized that as soon as we fire the secret weapon it stops being a secret, that's like 99% of the value of it - we must forever abstain from firing the secret weapon so that we always maintain a position of power where we have a secret weapon we can fire - but golly gee willikers make sure our enemies never discover our secret weapon!'
'Oh gosh, wait a moment, I just realized that as soon as we fire the secret weapon it stops being a secret, that's like 99% of the value of it - we must forever abstain from firing the secret weapon so that we always maintain a position of power where we have a secret weapon we can fire - but golly gee willikers make sure our enemies never discover our secret weapon!'