use this code
MailMessage oMsg = new MailMessage();
oMsg.From = new MailAddress("xxx@gmail.com", "xxx");
oMsg.To.Add(new MailAddress("yyy@gmail.com", "xxx"));
oMsg.Subject = "Packet Parsing Problem";
oMsg.Body = " Problem Occuread test mail";
oMsg.SubjectEncoding = System.Text.Encoding.UTF8;
oMsg.BodyEncoding = System.Text.Encoding.UTF8;
oMsg.IsBodyHtml = false;
oMsg.Priority = MailPriority.High;
SmtpClient oSmtp = new SmtpClient("smtp.gmail.com", 587);
oSmtp.DeliveryMethod = SmtpDeliveryMethod.Network;
oSmtp.EnableSsl = true;
NetworkCredential oCredential = new NetworkCredential("xxx@gmail.com", "123456aA");
oSmtp.UseDefaultCredentials = false;
oSmtp.Credentials = oCredential;
oSmtp.Send(oMsg);
Thanks