The industry got good at that, Google is not a magical spam filter in fact in some ways it is not even really that great at all.
There are many many ways to achieve the same or better results for spam protection they by using google
There are many many ways to achieve the same or better results for spam protection they by using google
It didn't get decent until it people started flocking toward centralized solutions like GMail, which (coincidentally or not) did a pretty decent job of reining in spam and viruses.