[WordPress] Code from our blog post - Changing the Default Outgoing WordPress Email Address - http://www.limecanvas.com/changing-the-default-outgoing-wordpress-email-address/

functions.php

function lc_new_mail_from( $email ) {
$email = 'hello@mydomain.com';

return $email;
}
add_filter( 'wp_mail_from', 'lc_new_mail_from' );

function lc_new_mail_from_name( $name ) {
$name = 'My Business Website';

return $name;
}
add_filter( 'wp_mail_from_name', 'lc_new_mail_from_name' );