Why would they end an email with "Singapore."? I've never seen a company sign a letter, much less an email, with a geographic location. It's not even an full address, which would make slightly more sense.
Again, the "@yahoo.com" is a huge give away. Most likely fake. Though the odd thing is, there's no link to click on or a website to go to. They just want you to email them back and they didn't request info like credit card numbers.
I think you should ignore the email.