unable to connect to the remote server c# smtp gmail

Question

public string SendMail(string Emailids, string subject, string body)

{

string eroorMessage = string.Empty;

try

{

string hostname = ConfigurationManager.AppSettings["contactHost"];

int portno = Convert.ToInt32(ConfigurationManager.AppSettings["contactPort"]);

string frommailid = ConfigurationManager.AppSettings["contactMail"];

string frompwd = ConfigurationManager.AppSettings["contactPassword"];

var sendlist = Emailids.Split(',');

var Tolen = sendlist.Length;

string to = "";

if (Tolen == 1)

{

to = Emailids.Trim(',');

}

else

{

for (int i = 0; i < Tolen; i++)

{

to = sendlist[i];

}

}

var smptClient = new SmtpClient(hostname, portno)

{

Credentials = new NetworkCredential(frommailid, frompwd),

EnableSsl = true

};

smptClient.Send(frommailid, to, subject, body);

return "scucess";

}

catch (Exception ex)

{

eroorMessage = ex.Message.ToString() + ex.StackTrace.ToString() + ex.InnerException.ToString();

return eroorMessage;

}

}