Mail Message in Window form application

Question

Dear Sir,

                 I have a code for mail message in window form application but I get exception error after running. Code is here

private void buttonSend_Click(object sender, EventArgs e)

{

try

{

MailMessage mail = new MailMessage(textBoxFrom.Text, textBoxTo.Text, textBoxSubject.Text, richTextBoxMsgBody.Text);

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

smtp.Credentials = new System.Net.NetworkCredential(textBoxOwnE.Text, textBoxPass.Text);

smtp.EnableSsl = true;

smtp.Send(mail);

MessageBox.Show("Your e-mail is sent suuccessfully!", "Message Sent", MessageBoxButtons.OK, MessageBoxIcon.Information);

}

catch (Exception ex)

{

MessageBox.Show(ex.Message);

}

}

Please help me . I shell be very thankful to you for this kindness.