If you have read about how to identify a scam email (which is here) then in addition to things like bad grammar, poor spelling, even poorer punctuation, the use of free email servers, etc. these are some other things that make a lottery scam format completely bogus.

I just won a lottery!
No you didn't. You just got a scam email.

1. Real lotteries never notify people by email like this. Never.
But maybe...no, not maybe. It is a scam. It is never real.
What if...? No, sorry it's a scam.
It could be....it is a scam. You are not a winner.
Just to repeat, real lotteries never notify people by email. What you have is a scam email and the best thing to do with it is to delete it and forget it.

2. If you didn't buy a ticket you can never win a lottery.
Hopefully it would go without saying but sometimes people do need to be reminded of this. It's just that simple. You buy a ticket, you can win. No ticket, no win. Lotteries make money by selling tickets. They do not make money giving money away. They have to sell tickets.

3. "No tickets were sold"
This is a cute little fiction that scammers have cooked up to explain why you can win without buying a ticket (see #2). If they didn't sell tickets then it isn't a real lottery.

4. I won the Microsoft lottery.

Sorry, you didn't. Microsoft doesn't have a lottery. Most of the lotteries listed in this forum are not real lotteries. A few of them are but if you didn't buy a ticket, you can't win.

5. I won the Australian lottery but my claims agent is in Nigeria.
Think about that one for a minute. Take a look at a map. See Australia? See Nigeria? Why would Australians hire people in Nigeria to be paying agents for their lottery? It's not logical and it makes no sense economically. Your "paying agent" in Nigeria is actually just a criminal/scammer.

This goes for any other country with a lottery in one country but the paying agent in another. If they tell you that, it's just a scam email. Best to delete it and forget it.

6. Your lottery winnings are covered by a "high insurance policy".
Cute, but entirely fictitious. This is a little device the scammers have created (in their own mind) to explain why they can't deduct the fees from all that lottery money you won. There is no such thing as a "high insurance policy". The reason they cant, or won't deduct the fees from the winnings is because there are no winnings. (See # 1-3 above).