Use File Upload Control
MailMessage msg1 = new MailMessage();
string from = "Email address";
string ps = "Email Password";
string sub = TextBox1.Text + "Welcome to the world of Travel!";
msg1.From = new MailAddress(from, "Way2hotel");
msg1.To.Add(new MailAddress(TextBox5.Text));
msg1.Subject = sub;
msg1.Body = "Congratulations,Thanks for Signing up.Celebrate increased growth in revenue.Enjoy your Bookings,Offers and promos with way2hotel.";
msg1.IsBodyHtml = true;
if (RadioButtonList3.Text == "Yes")
{
if (inpAttachment1.PostedFile != null)
{
HttpPostedFile attFile = inpAttachment1.PostedFile;
int attachFileLength = attFile.ContentLength;
if (attachFileLength > 0)
{
strFileName = Path.GetFileName(inpAttachment1.PostedFile.FileName);
inpAttachment1.PostedFile.SaveAs(Server.MapPath(strFileName));
MailAttachment attach = new MailAttachment(Server.MapPath(strFileName));
msg1.Attachments.Add(attach);
attach1 = strFileName;
}
SmtpClient smtp = new SmtpClient();
smtp.Host = "HOST NAME";
smtp.Port = PORT NUMBER;
smtp.Credentials = new NetworkCredential(from, ps);
re.Visible = true;
smtp.EnableSsl = true;
}