Probably a spoofed Email, did they give an address to send the Bitcoin in the email? Of course, don’t send it.
It's not a spoofed email, Yobit is sending that kind of offers regularly and this particular email is from them. I got it too.
But OP, don't fool yourself to use the offer. It comes with some restrictions, Yobit token holding, etc., and you could end up with locked coins there.