email notification from WordPress [wordpress@mysite.com]

Hi
Anytime that wordpress sends me an email, it is sent from
"WordPress [wordpress@pruebas.massantia.com]"
how do i have to do to change this, because i want that my clients, users or whoever receive the mails from my site, can see my site's email address nor wordpress.

whatever@mysite.com

Is that posible?

Thanks