问如何使用CSharp和代理网络通过SMTP协议发送电子邮件？

EN

    MailMessage mm = new MailMessage("sender@gmail.com", txtEmail.Text.Trim());
        mm.Subject = "Password Recovery";
        mm.Body = string.Format("Hi {0},<br /><br />Your password is {1}.<br /><br />Thank You.", username, password);
        mm.IsBodyHtml = true;
        SmtpClient smtp = new SmtpClient();
        smtp.Host = "smtp.gmail.com";
        smtp.EnableSsl = true;
        NetworkCredential NetworkCred = new NetworkCredential();
        NetworkCred.UserName = "sender@gmail.com";
        NetworkCred.Password = "senderpassword";
        smtp.UseDefaultCredentials = true;
        smtp.Credentials = NetworkCred;
        smtp.Port = 587;
        smtp.Send(mm);
        lblMessage.ForeColor = Color.Green;
        lblMessage.Text = "Password has been sent to your email address.";