I maintain a Hotmail account. It is convenient for those subscriptions, registrations, and other sign-ups that, should my account get inundated by spam, I could easily abandon.
Over the last month, I have noticed that the spam filter consistently misses obvious spam. Misses it even after the offending topic and approach have been marked as spam and reported. Are these spammers paying a premium for delivery? Or are the Hotmail coders just missing the boat?
My Yahoo! and gmail accounts work fine. If anything, their spam filters are a tad too aggressive. But once marked, a spam approach never succeeds again.
I have noticed this too, although I have been less systematic about observing it. I figured the increased spam on Hotmail was because it is such a big target. Still, it seems like a lot of obvious crap gets through the filters.
And keeps getting through the filters after the spam has been reported as such.