Even when spam doesn't get to your inbox, it uses up bandwidth. The necessary increased filtering also risks blocking genuine e-mails.

I would go so far as to say that, not only is Microsoft wrong about the reduction of spam, but they are actually part of the problem. Microsoft could, for example, more aggressively attack spammers operating off Microsoft-owned Hotmail accounts.

It won't reduce spam directly. AOL is already good at managing spam issues, and Yahoo is getting better. It may make it easier to filter mail, and may provide more resources for spam prevention, but it could also mean that people lose emails, and so change provider.

Given what I know of spam, [filtering won't] be very effective in reliably differentiating types of spam, without requiring large amounts of manual intervention,

When it comes to Spam, ... we get the joke.

Porn is passe when it comes to spam.