Send Email with attachment of 23 MBusing C#

try
{
    mail = new MailMessage();
    mail.To.Add(ConfigurationManager.AppSettings["PaypalEmail2"].ToString());
    mail.From = new MailAddress("abc@gmail.com");
    mail.Subject = "File Downloaded to VAM";
    mail.Body = "Name : " + txtName.Text + "\n Contact Details : " + txtPhone.Text + "\n Email ID :" + txtEmail.Text + "\n";
    mail.IsBodyHtml = true;

    if (flpFile.HasFile)
    {
        mail.Attachments.Add(new Attachment(flpFile.PostedFile.InputStream, flpFile.FileName));
    }
    smtp = new SmtpClient();
    smtp.Host = "smtp.gmail.com";
    smtp.Credentials = new System.Net.NetworkCredential("abc@gmail.com", "sample");
    smtp.EnableSsl = true;
    smtp.Send(mail);

    txtEmail.Text = txtName.Text = txtPhone.Text = string.Empty;
}
catch (Exception ex)
{
          // so something 
}
finally
{
    mail = null;
    smtp = null;
}