No, it's real. I gave it up a year ago, after hosting my own mail since forever. Exactly as stated: Hotmail (or whatever MS mail is called these days), GMail etc. are the main culprits. So yes, 'colossal' is the word.
Hashcash, Bitcoin's PoW game, was intended for use as an email attachment to create a real cost to spam without any micropayments.
"If you want to mail me, prove that you burned five seconds of CPU time."