首先，在开始使用Asp.net Core邮件发送器之前，您需要在Startup.cs文件的ConfigureServices方法中进行配置。在这里，您应该注册IEmailSender服务，并指定实现此服务的类。例如：

using Microsoft.Extensions.DependencyInjection;
using Microsoft.AspNetCore.Identity.UI.Services;
using MyNamespace.Services; // The namespace where your EmailSender resides
...

public void ConfigureServices(IServiceCollection services)
{
    ...
    services.AddTransient();
}

您需要创建一个名为EmailSender的类，并从IEmailSender接口派生它。这个新类应该覆盖SendEmailAsync方法，并使用您选择的电子邮件传输方式（例如SMTP）发送电子邮件。以下是一个示例：

using System.Threading.Tasks;
using Microsoft.AspNetCore.Identity.UI.Services;

namespace MyNamespace.Services
{
    public class EmailSender : IEmailSender
    {
        public Task SendEmailAsync(string email, string subject, string message)
        {
            // TODO: Use your chosen email transport method (e.g. SMTP) to send the email
            return Task.CompletedTask;
        }
    }
}

在你的Registration页面上，你应该注入IEmailSender服务，然后调用SendEmailAsync方法发送电子邮件。以下是一个示例Registration页面的代码：

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Identity.UI.Services;
using System.Threading.Tasks;
using MyNamespace.ViewModels;

namespace MyNamespace.Controllers
{
    public class AccountController : Controller
    {
        private readonly UserManager _userManager;
        private readonly SignInManager _signInManager;
        private readonly IEmailSender _emailSender;

        public AccountController(
            UserManager userManager,
            SignInManager signInManager,
            IEmailSender emailSender)
        {
            _userManager = userManager;
            _signInManager = signInManager;
            _emailSender = emailSender;
        }

        [HttpGet]
        public IActionResult Register()
        {
            return View();
        }

        [HttpPost]
        public async Task Register(RegisterViewModel model)
        {
            if (ModelState.IsValid)
            {
                var user = new ApplicationUser { UserName =