You cannot be 100% sure that the email is coming from who you think it is. Email accounts get hacked all the time. And there are a lot of tricks they can use as well. For instance ... your email id is somebody@yahoo.com and the scammers can set up a somebody@gmail.com. No one can remember everybody else's actual email address. If it looks fake, don't answer. If you do, then they just verified your email id. If it looks real, you still have to ask the right questions to make sure who is actually sending the emails.