There is no point in wasting your time worrying about Spam or trying to stop it. It will never be possible to stop Spam as long as accreditation is given to companies to sell domains that have no intension of following any of the rules.
Combine that main factor with the thousands of servers that will relay any email because they are not set up correctly and you have an impossible situation. A situation that could be changed for the better tomorrow but it will not.
These domain registrars that know how to pay the game are making millions of dollars and so is the company that give them the rights to sell domains.
