Will this decrease the Spammers?
Probably not, but it will force spammers to looking for new ways to come thru to us.
Now have Sweden MKL Invest or Mailadresser.nu started are threatening with court if you reporting the mail as spam.
Obviously, there are no court in the world that would judge in favor of a spammer in this thing, but it creates one unsecured feeling among those who feel spammed.
The cost of spam mails for a company is not cheap, its calculated that for a company with 150-200 employer have an annual cost around 7500 € ($ 6700) in lost time