I have an ASP.NET application hosted on Godaddy that I want to send email from. When it runs, I get: Mailbox name not allowed. The server response was: sorry, relaying denied from your location. The important parts of the code and Web.config are below:

msg = new MailMessage("[email protected]", email);
        msg.Subject = "GreekTools Registration";
        msg.Body =
            "You have been invited by your organization to register for the GreekTools recruitment application.<br/><br/>" +
            url + "<br/><br/>" +
            "Sincerely,<br/>" +
            "The GreekTools Team";

        msg.IsBodyHtml = true;

        client = new SmtpClient();
        client.Host = "relay-hosting.secureserver.net";

        client.Send(msg);

<system.net>
<mailSettings>
  <smtp from="[email protected]">
    <network host="relay-hosting.secureserver.net" port="25" userName="********" password="*********" />
  </smtp>
</mailSettings>