If you are not sure about such an email is legitimate reach out to a rep for the sponsor *supposedly* sending email as it may be a scammer impersonating them. Do NOT reply or click any links in such email until you get verification that it is a legit email.
If you are 17 you should not even touch Sarms or God forbid, AAS. Train naturally and take in plenty of protein and then you'll get there. Don't screw up your body at this stage as you are still developing.