When you register a domain name, your contact information is recorded in the WHOIS database and becomes publicly available. Your information is made public in order to allow rapid resolution of technical problems and to permit enforcement of consumer protection, trademark, and other laws.
In order to protect your private contact information, you can get the Private Registration service. This feature allows you to hide your data, while the WHOIS company provides its contact information (and a fake email address) to replace your own. The Private Registration service protects you from spammers, unsolicited marketing and identity theft - problems quite common over the Internet. Joomlinux offers Private Registration for domains registered by Joomlinux for $24.95 per year. You can order it from your Customer Area.