[Grimburger]

Certainly, but I don't see anyone trying to properly stop it in both cases here?

Amusingly the PoW as we know it in cryptocurrency came from attempts to combat email spam with HashCash, it's clearly referenced in the Bitcoin whitepaper as a precursor.

[hazmazlaz]

I am not sure if I am correctly interpreting your question here, but if I am then I can assure you that a great deal of time/energy/resources are devoted to stopping spamming/scamming, particularly over email. There is an entire public-private industrial sector focused on doing so and many billions of dollars per year are spent towards that end.