I’ve actually told a few friends that manage websites to have their own email with their domain as the site url. Some listen and some don’t. Why should you have an email that tells everyone that you are the adminstrator of that site? Well first it seems a lot more professional than having just a yahoo or gmail account. And second people will know that the email address is linked to the site. Nobody wants to give away information to someone if they aren’t sure who they are giving it to.
If you have a domain just go to your web host control panel or domain control panel and set up an admin email. You can always set it to forward all the mail to your other email account whether its yahoo, gmail, or anything else. You have to know what your visitors questions are and then you can help them all out.