I do not believe Yahoo Mail's assertion here. I have a Y! Mail account (which I do check once a week) and almost 80% of mails are spam. So they are not doing a

I do not believe Yahoo Mail's assertion here. I have a Y! Mail account (which I do check once a week) and almost 80% of mails are spam. So they are not doing a good job at it (vs. GMail which is the other email provider I use) and thus their metrics here look skewed to me.