Try this one
try
{
string mailBody = String.Empty;
System.Net.Mail.MailMessage objMessage = new System.Net.Mail.MailMessage();
objMessage.IsBodyHtml = true;
objMessage.Subject = "Issue Response Details";
objMessage.Body = "your message";
objMessage.To.Add("toemailid");
objMessage.From = new MailAddress("fromemailid");
System.Net.Mail.SmtpClient smtp = new System.Net.Mail.SmtpClient();
ServicePointManager.ServerCertificateValidationCallback = delegate(object s, System.Security.Cryptography.X509Certificates.X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) { return true; };
smtp.Send(objMessage);
}
catch (Exception ex)
{
throw ex;
}