private void UpdateControls()
        {
            bool OK = true;

            if (OK && String.IsNullOrEmpty(textbox_ServerAddress.Text))
            {
                OK = false;
            }
            if (OK && checkbox_RequiresAuthentication.Checked)
            {
                if (String.IsNullOrEmpty(textbox_LogonName.Text))
                {
                    OK = false;
                }
                else
                if (String.IsNullOrEmpty(textbox_Password.Text))
                {
                    OK = false;
                }
            }

            string from = textbox_FromName.Text.Trim();

            from = (from.Length == 0) ? textbox_FromAddress.Text : String.Format("{0}<{1}>", from, textbox_FromAddress.Text);
            if (OK && (String.IsNullOrEmpty(from) || !NotificationProvider.IsMailAddressValid(from, true)))
            {
                OK = false;
            }

            if (m_DataOKDelegate != null)
            {
                m_DataOKDelegate(OK);
            }
        }