are you wanting to email a LINK to the current page, or email THE PAGE itself?
either way, to make sure the person doesn't have to have an email client (which will have to open up if you use that mailto: link), you should have the "Email this Article" link actually open up a PHP page with a form on it (as DaButcher suggested) where they put in an email address to send it to, and optional name, who it's from, etc. The Form would post back to itself, which has PHP script in it to do the mail'ing. That PHP script will use the PHP mail() function to have the Web Server send the email, rather than relying on the client to send it.
Then, you decide if that will email them just a simple email with the LINK in it, which the recipient can click, which is easily done by just putting the text of the fully qualified URL into the message body (
Or, if you want the whole article itself emailed to them, (text, pictures, etc), consider using ob_start() and it's associated functions... this turns on output buffering... so you can have the code which generates the page for the article, and capture that into a variable, and then send that whole value via email, which will give them an HTML email that looks like your webpage with the article on it.