Sending mail

Hi,
   Iam using below code for sending a mail, but its not storing in my sent mail option, how can i see that one in sentmail and how can i find that mail size?

 MailMessage msg = new MailMessage();
        msg.From = new MailAddress((TextBox1.Text));
        msg.To.Add((TextBox4.Text));
        if (FileUpload1.HasFile)
       {
           string fileName =FileUpload1.PostedFile.FileName;
           Attachment myAttachment =
                          new Attachment(FileUpload1.FileContent, fileName);
           m ...