SF_10.1, SF_10.2 - https://docs.sitefinity.com/tutorial-run-custom-code-when-a-product-is-added-to-wish-list

CustomCodeWithProducts_Global.asax.cs

using System;
using Telerik.Sitefinity.Abstractions;
using Telerik.Sitefinity.Modules.Ecommerce.Events;
using Telerik.Sitefinity.Services;

namespace SitefinityWebApp
{
    public class Global : System.Web.HttpApplication
    {

        protected void Application_Start(object sender, EventArgs e)
        {
            Bootstrapper.Initialized += new EventHandler<Telerik.Sitefinity.Data.ExecutedEventArgs>(Bootstrapper_Initialized);
        }

        private void Bootstrapper_Initialized(object sender, Telerik.Sitefinity.Data.ExecutedEventArgs e)
        {
            if (e.CommandName == "Bootstrapped")
            {
                EventHub.Subscribe<ProductAddedToWishlistEvent>(OnProductAddedToWishlist);
                EventHub.Subscribe<ProductInWishlistPurchasedEvent>(OnProductInWishlistPurchased);
            }
        }

        private void OnProductInWishlistPurchased(ProductInWishlistPurchasedEvent @event)
        {
            //do custom logic like send email here
            //@event.ProductId;
            //@event.ProductVariationIds;
            //@event.WishlistId;
        }

        private void OnProductAddedToWishlist(ProductAddedToWishlistEvent @event)
        {
            //do custom logic like send email here
            //@event.ProductId;
            //@event.ProductVariationIds;
            //@event.WishlistId;
        }
    }
}