If you own a domain and your name/address are shown on your WHOIS (the public information available for the owner of a domain) — chances are you’ve received a physical letter from Domain Registry of America (DROA) or Domain Registry.
DO NOT PAY THEM.
While they say in their letter (if you read it) that their letter is ‘not’ a bill, it looks a lot like a bill, and they have tricked many people.
You do not need to pay them to renew your domain — pay whoever it is registered with (Godaddy, Register.com, etc).
An example letter: