mailto: hyperlink opens blank page on site?

Chances are you've accidentally included a blank target in the links. Take a look at your source code for your mailto links and remove this if you see it...

target="_blank"

For what it's worth, mailto links are a bad way to get viewers to contact you. Nothing happens when anyone who doesn't use Outlook, Apple Mail or another dedicated email client clicks the link. It's much better to either just give them the email address without a link, or use a server-side form to email script instead.

You need to show us the code.

By the way, no one ever uses mailto any longer. It only works if the user has a mail client set up on their computer, which is often not the case. Usually people use the PHP mail function.