How to find e-mail address by web site

Hi,
Is there a way to find out e-mail address of website that do not display one?
Thank you.

If you have access to a Linux system, open a terminal and type "whois domain-you-want.com" to get a whois listing.
If you're like a browser-based solution, you can use a site like http://whois.domaintools.com/ to get the whois information.

whois information generally includes some sort of contact email address.

...and even if the domain has WHOIS protection enabled (meaning the information displayed is that of a third party), you can still send an email to the email address listed, and it will be forwarded to the domain owner.