Gmail’s SMTP server requires you to authenticate your request with a valid gmail email/password combination. You do need SSL enabled as well. Without actually being able to see a dump of all your variables being passed in the best guess I can make is that your Credentials are invalid, make sure you’re using a valid GMAIL email/password combination.
You might want to read here for a working example.
EDIT: Okay here’s something I wrote and tested just then and it worked fine for me:
public static bool SendGmail(string subject, string content, string[] recipients, string from) {
if (recipients == null || recipients.Length == 0)
throw new ArgumentException("recipients");
var gmailClient = new System.Net.Mail.SmtpClient {
Host = "smtp.gmail.com",
Port = 587,
EnableSsl = true,
UseDefaultCredentials = false,
Credentials = new System.Net.NetworkCredential("******", "*****")
};
using (var msg = new System.Net.Mail.MailMessage(from, recipients[0], subject, content)) {
for (int i = 1; i < recipients.Length; i++)
msg.To.Add(recipients[i]);
try {
gmailClient.Send(msg);
return true;
}
catch (Exception) {
// TODO: Handle the exception
return false;
}
}
}
If you need any more info there’s a similar SO article here