SmtpClient smtpclient;
        MailMessage message;
            string str234 = "Name=" + txtname.Text + "\n Address=" + txtaddress.Text 

            + "" + "'\n Phone No=" + txtmobileno.Text + "\n Fax No=" + txtfax.Text

            + "\n Email=" + txtemail.Text + "\n Message=" + txtmessage.Text;

            smtpclient = new SmtpClient();
            message = new MailMessage();

            message.From = new MailAddress("developerlifestyle@gmail.com");
            message.To.Add("developerlifestyle@gmail.com");  //send email to gmail

            message.Subject = "Contact Form";
            message.Body = str234;
            smtpclient.Host = "smtp.gmail.com";
            smtpclient.EnableSsl = true;
            smtpclient.UseDefaultCredentials = true;
            System.Net.NetworkCredential network = new System.Net.NetworkCredential();
            network.UserName = "developerlifestyle@gmail.com"; 
            network.Password = "*******"; //password
            smtpclient.UseDefaultCredentials = true;
            smtpclient.Credentials = network;
            smtpclient.Port = 25;
            smtpclient.Send(message);