First, you are going to add a new email service, which will be used to send emails to users who have freshly registered on the website. Let's get started:

1. Within the Services folder, add a new service called EmailService and implement a default SendEmail method, which we will update later:

        public class EmailService 
        { 
          public Task SendEmail(string emailTo, string subject,
           string message) 
          { 
            return Task.CompletedTask; 
          } 
        } 

2. Extract the IEmailService interface:

3. Add the new email service to the ConfigureServices method of the Startup class (we want a single application instance, so add it as a singleton):

        services.AddSingleton<IEmailService, EmailService>(); 

4. Update UserRegistrationController so that it is able to access EmailService, which we created in the previous step:

        readonly IUserService _userService; 
        readonly IEmailService _emailService; 
        public UserRegistrationController(IUserService userService,
         IEmailService emailService) 
        { 
          _userService = userService; 
          _emailService = emailService; 
        } 

5. Update the EmailConfirmation method in UserRegistrationController so that you can call the SendEmail method of EmailService by inserting the following code between var user=await _userService.GetUserByEmail(email); and the user?.IsEmailConfirmed conditional statement check:

          var user = await _userService.GetUserByEmail(email); 
          var urlAction = new UrlActionContext 
          { 
            Action = "ConfirmEmail", 
            Controller = "UserRegistration", 
            Values = new { email }, 
            Protocol = Request.Scheme, 
            Host = Request.Host.ToString() 
          }; 
 
          var message = $"Thank you for your registration on
             our website, please click here to confirm your
             email " +   $"
            {Url.Action(urlAction)}";
 
          try 
          { 
            _emailService.SendEmail(email,
             "Tic-Tac-Toe Email Confirmation", message).Wait(); 
          } 
          catch (Exception e)    {    } 

Great – you have an email service now, but you aren't done yet. You need to be able to configure the service so that you can set environment-specific parameters (SMTP server name, port, SSL, and more) and then send the emails.