Three years ago, Bill said that his toy factory will eradicate spam in two years. That two years ended one year ago and we still see spam. The nice thing about the spam we see these days is that is generated by the spammeisters who are paid by the amount of spam sent and how quickly it is sent and not if those are delivered/rejected.
Because the systems that are being used to generate spam are running Windows exclusively, the spam merchants have taken to implementing an email sending scheme that is not fully compliant with the standard SMTP protocols. Because these chaps have to send out mail in a hurry, they don’t care for error conditions etc and so the concept of greylisting is therefore eminently capable of taking care of this Microsoft hosted/generated nuisance.
So, thanks Bill for actually solving the problem by having crap operating systems that take over so much resource within the computer that the purveyors of spam have to resort to an abbreviated SMTP protocol to get their cash. Whether you like it or not, Bill, Windows has helped solve the spam issue.