Pour créer un nouveau statut de commande et envoyer un e-mail personnalisé sur votre boutique woocommerce.

/* Ajout status de commande perso et envoi d'emails */
// register a custom post status 'ready-pickup' for Orders
add_action( 'init', 'register_custom_post_status', 20 );
function register_custom_post_status() {
    register_post_status( 'wc-ready-pickup', array(
        'label'                     => _x( 'Prête à emporter', 'Order status', 'woocommerce' ),
        'public'                    => true,
        'exclude_from_search'       => false,
        'show_in_admin_all_list'    => true,
        'show_in_admin_status_list' => true,
        'label_count'               => _n_noop( 'Prête à emporter <span class="count">(%s)</span>', 'Prête à emporter <span class="count">(%s)</span>', 'woocommerce' )
    ) );
}

// Adding custom status 'ready-pickup' to order edit pages dropdown
add_filter( 'wc_order_statuses', 'custom_wc_order_statuses', 20, 1 );
function custom_wc_order_statuses( $order_statuses ) {
    $order_statuses['wc-ready-pickup'] = _x( 'Prête à emporter', 'Order status', 'woocommerce' );
    return $order_statuses;
}

// Adding custom status 'ready-pickup' to admin order list bulk dropdown
add_filter( 'bulk_actions-edit-shop_order', 'custom_dropdown_bulk_actions_shop_order', 20, 1 );
function custom_dropdown_bulk_actions_shop_order( $actions ) {
    $actions['mark_ready-pickup'] = __( 'Marquer Prête à emporter', 'woocommerce' );
    return $actions;
}

// Adding action for 'ready-pickup'
add_filter( 'woocommerce_email_actions', 'filter_woocommerce_email_actions');
function filter_woocommerce_email_actions( $actions ) {
    $actions[] = 'woocommerce_order_status_wc-ready-pickup';
    return $actions;
}

//add_action( 'woocommerce_order_status_wc-ready-pickup', array( WC(), 'send_transactional_email' ), 10, 1 );

// Sending an email notification when order get 'ready-pickup' status
add_action('woocommerce_order_status_ready-pickup', 'backorder_status_custom_notification', 20, 2);
function backorder_status_custom_notification_old($order_id, $checkout=null) {
   global $woocommerce;
   $order = new WC_Order( $order_id );
   if($order->status === 'ready-pickup' ) {
        // Create a mailer
        $mailer = $woocommerce->mailer();

        $message_body = __( 'Hello world!!!' );

        $message = $mailer->wrap_message(
            // Message head and message body.
            sprintf( __( 'Order %s received' ), $order->get_order_number() ), $message_body
        );

        // Cliente email, email subject and message.
        $mailer->send( $order->billing_email, sprintf( __( 'Order %s received' ), $order->get_order_number() ), $message );
     }

}

function backorder_status_custom_notification( $order_id, $order ) {
    // custom settings
    $heading   = __('Votre commande est prête !','woocommerce');
    //$subject   = '[{site_title}] Votre commande est prête ({order_number}) - {order_date}';
    $subject   = 'Votre commande est prête !';

    // Getting all WC_emails objects
    $mailer = WC()->mailer()->get_emails();

    // Customizing Heading and subject In the WC_email processing Order object
    $mailer['WC_Email_Customer_Processing_Order']->heading = $heading;
    $mailer['WC_Email_Customer_Processing_Order']->settings['heading'] = $heading;
    $mailer['WC_Email_Customer_Processing_Order']->subject = $subject;
    $mailer['WC_Email_Customer_Processing_Order']->settings['subject'] = $subject;
    $mailer['WC_Email_Customer_Processing_Order']->template_html = 'emails/ready-pickup.php';
    $mailer['WC_Email_Customer_Processing_Order']->template_plain = 'emails/plain/ready-pickup.php';

    // Sending the customized email
    $mailer['WC_Email_Customer_Processing_Order']->trigger( $order_id );
}