If you do not have an SMTP server of your own, you can still send SMTP authenticated emails from your .net application. Just sign up for a brand new gmail account or use your exisiting gmail account.

SmtpClient obj = new SmtpClient(“smtp.gmail.com”,465);
//465 is the TCP port for sending emails using gmail. 465 is generally used for SMTP with SSL.

obj.EnableSsl = true;
obj.Credentials=new System.Net.NetworkCredential(“username@gmail.com”, “password”);
// your email address and its password for the SMTP authentication

MailMessage Mailmsg = new MailMessage();
Mailmsg.To.Clear();
Mailmsg.From = new MailAddress(“username@gmail.com”);
Mailmsg.Subject = “Subject”;
Mailmsg.Body =”Body”;

//adding attachments
Attachment at = new Attachment(Server.MapPath(“~/document.doc”));
Mailmsg.Attachments.Add(at);
Mailmsg.Priority = MailPriority.High;
Mailmsg.IsBodyHtml = true;
Mailmsg.To.Add(new MailAddress(“mailaddress”, “name”));
Mailmsg.BodyEncoding = System.Text.Encoding.Default;
try
{

obj.Send(Mailmsg);

}
catch (Exception ex)
{

Response.Write(ex.Message.ToString());

}