SmtpClient sMTPClient = new SmtpClient();
sMTPClient.EnableSsl = true;
sMTPClient.Host = "smtp.gmail.com";
sMTPClient.Port = 587;
sMTPClient.UseDefaultCredentials = false;
sMTPClient.Credentials = new System.Net.NetworkCredential("sender's email Address", "password");
sMTPClient.DeliveryMethod = SmtpDeliveryMethod.Network;
sMTPClient.Send(mailMessage);