Obviously this is most likely a scam...how do i report it?

It's what is commonly referred to as "a Nigerian scam". This one has wide circulation, no need to report it. You cannot win a lottery that you did not buy a ticket in. Use common sense. Lotteries do not just take your name out of the air and do you really believe that MSN, Hotmail, AOL, AltaVista, Google and "others" are going to give a list of all their email address's to Yahoo. I have investigated Internet fraud and scams for years. I am a retired Police Officer and the scams asked about on this site are the more basic stupid ones that with a minimal amount of research you would find out it's a scam. This particular one will either send you a counterfeit check to pay taxes or request your personal information. The checks for the most part are counterfeit and when your bank discovers this you are held liable. They will want you to cash the check and send the tax payment by an wire service. Here how lotteries work. You must pay to play, if you didn't then then you can't possibly win.