how to send mail

Question

This Code is using For Sending Mail

but i Dont Sent the mail. Can anyone help Me ASAP.

 

using (MailMessage mail = new MailMessage())

{

mail.From = new MailAddress("[email protected]");

mail.To.Add(textbox3.Text);

mail.Subject = "Random Password for your Account";

mail.Body = "You Are Successfully Register...!!!\n\nDear " + textbox1.Text + "," + "\n" + strNewPassword + "," +

"\n\tThank you registering for Onlile Shopping As A Member." +

"\nIf you have any query please contact 8319058205." +

"\nThank you and Have a nic Day....!" +

"\n\n[Mr.Shubham Agrawal]";

mail.IsBodyHtml = false;

SmtpClient smtp = new SmtpClient();

smtp.Host = "smtp.gmail.com";

smtp.EnableSsl = true;

NetworkCredential networkCredential = new NetworkCredential();

networkCredential.UserName = "[email protected]";

networkCredential.Password = "*******";

smtp.UseDefaultCredentials = true;

smtp.Credentials = networkCredential;

smtp.Port = 587;

smtp.Send(mail);

ClientScript.RegisterStartupScript(GetType(), "alert", "alert('Message has been sent successfully.');", true);

}