Errrr - what? This must be one of the shortest scam emails ever. This scammer is so lacking in imagination that s/he can't even be bothered to make up a story telling you what/why you are getting money.
You aren't going to get any money. It's a scam. Why on earth would anyone email you out of the blue to tell you to email them and claim $800k? If you answer, all you will get is a scammer asking you for money to pay for "fees". Delete the email and don't reply.
Send Details to ( firstname.lastname@example.org) for claims of $800,000