4 Answers

Basically if an e-mail is offering you money when you never initiated anything to receive money from an unknown person or entity  then you can be sure it's a scam, especially if it asks for personal information like bank account numbers in order for you to receive the money. 

send them some cash and wait for a response, when none arrives you know you have been scammed! but seriously, there is no such thing as FREE CASH! so whenever you get one of these emails, delete and block. :-)

I've received many scamming emails and when I Googled the sender, I found many negative records. Anything coming out of Nigeria should raise a "red flag". Query "419 scams".

You don't need to find out, if someone is offering you money or anything else for nothing, it's a scam.