No!! Well then you are one of the fortunate ones unfortunately many people fall prey to very simple scams. In particular the biggest one going is around domain registration. Recently a client of mine was scammed on their domain name and getting out of it is a bit of work here is the drill.
A company called US Domain Registrar (who is actually reseller for ENOM.com and not a true registrar) send out the faxes with some great legal mumbo-jumbo on them designed to scare you into believing you are losing your domain or to get you to register a variation of your current domain i.e. the .us version vs. the .com version.
This fax or email as is often the case seem so legit that many folks who do not know how the registration of their domain is handled fall for the bait and send them money. The company US Domain Registrar then charges you $60US (domains are anywhere from $8US year and up) per year for the domain and what do they do is they registrar the domain in their name not yours and in their paper work say they point it to your current domain. In practice what they do is point the domain to an advertising page and make money off your twice once for the registration and once for the ads that show when people click them.
So if you see one of the emails or faxes do not send them money, do not give them your credit card, first check with your web designer about your domain. A reputable web designer will help you maintain the proper registration of your domain and any alternates you may want or need. Most of all do not send any money to US Domain Registrar it is a scam.