The sample below used SmtpClient to send e-mail from your gmail account using your gmail username and password.

using System;

using System.Net;

using System.Net.Mail;

namespace GMailSample

{

    class SimpleSmtpSend

    {

        static void Main(string[] args)

        {

            SmtpClient client = new SmtpClient("smtp.gmail.com", 587);           

            client.EnableSsl = true;

            MailAddress from = new MailAddress("YourGmailUserName@gmail.com", "[ Your full name here]");           

            MailAddress to = new MailAddress("your recipient e-mail address", "Your recepient name");

            MailMessage message = new MailMessage(from, to);

            message.Body = "This is a test e-mail message sent using gmail as a relay server ";

            message.Subject = "Gmail test email with SSL and Credentials";

            NetworkCredential myCreds = new NetworkCredential("YourGmailUserName@gmail.com", "YourPassword", "");           

            client.Credentials = myCreds;

            try

            {

                client.Send(message);

            }

            catch (Exception ex)

            {

                Console.WriteLine("Exception is:" + ex.ToString());

            }

            Console.WriteLine("Goodbye.");

        }

    }

}