Pretty nifty side point: > If enough people do this the cost of those bouncing emails would become prohibitive. This idea got a ton of attention in early days

Pretty nifty side point: > If enough people do this the cost of those bouncing emails would become prohibitive. This idea got a ton of attention in early days tech that led to what's known as proof of work: see bitcoin. The primitives of btc show up in a lot of interesting areas.