Send them the link to your places page....and then they need to sign in to give you a review
When they click the sign in to rate button...It will give them the option to sign up if they don't have a gmail account.
Just right click on that link...cut and paste it into an email
Tell the customer to look for the "sign in to rate" button OR they can click on the empty stars at the top....Where it says "Your Rating"
Hope this helps.