Disable new site creation email notifications for WordPress multisite

In multisite, WordPress 3.0.5 will send new site creation email notifications to the site admin by default. There’s also no super admin option to disable them. Fortunately, a short code snippet in /wp-content/mu-plugins/ achieves the same effect:

function db_remove_new_site_notification_email( $blog_id, $user_id, $password, $title, $meta ) {
return false;
}
add_filter( 'wpmu_welcome_notification', 'db_remove_new_site_notification_email' );

Behind the scenes, we’re hijacking a filter in wpmu_welcome_notification() to invalidate the method and disable the email. With this approach, the option to email the network administrator is still functional.