using System.ComponentModel.DataAnnotations;
public class EmailsService
private readonly SmtpClient _smtpClient = new();
private bool ValidateEmail(string email)
return email.Contains("@");
public void SendEmail(MailMessage message)
_smtpClient.Send(message);
public EmailService _emailService;
public UserService(EmailService emailService)
_emailService = emailService;
public void Register(User user)
if (!_emailService.ValidateEmail(user.email))
throw new ValidationException("Invalid Email");
_emailService.SendEmail(new MailMessage("mysite@nowhere.com", user.email) { Subject = "Welcome" });