Wordpress - Disable new user notification to admin email

There are several ways to prevent user notification for new registered users and user password changes.

One would be to change the pluggable functions "wp_new_user_notification()" and "wp_password_change_notification()". A different way would be to post the following code in functions.php.

It uses the "phpmailer_init" hook to test, if the subject of the mail is the one sent by "wp_new_user_notification" and "wp_password_change_notification". If the condition is met then the $phpmailer object is newly initialized. That means it is empty and cannot be sent since phpmailer class checks if there is at least a single recipient.

// prevent admin notification email for new registered users or user password changes
function conditional_mail_stop() {
    global $phpmailer;
    $blogname = wp_specialchars_decode(get_option('blogname'), ENT_QUOTES);
    $subject = array(
        sprintf(__('[%s] New User Registration'), $blogname),
        sprintf(__('[%s] Password Lost/Changed'), $blogname)
    );
    if ( in_array( $phpmailer->Subject, $subject ) )
        // empty $phpmailer class -> email cannot be send
        $phpmailer = new PHPMailer( true );
}
add_action( 'phpmailer_init', 'conditional_mail_stop' );