It's just either a phishing link, or someone is messing with you. If it's the latter, someone probably found your email on some forum account of yours. Probably just ignore the email and just not activate the account so the registration would be nullified(hopefully).
Ignoring is the best way.
Sometimes we do not care to post our email addresses in the forums or we just subscribes with this and that promotions. These people basically sell the data (your email address). The buyers then misuse the contacts.
This is the reason I do not subscribe with the websites or any kind of promotions that I do not trust.