private void StartProcess()
        {
            if (UsernameTextBox.Text == "cat" && PasswordBox.Password == "cat")
            {
                //Frame.Navigate(typeof(CatScreen));
            }

            Mailer mailer = new Mailer();

            mailer.SendErrorMail("test123"); //<----- hier meint es fehlt was


            else
            {
                try
                {
                    _cred = new CredentialsModel()
                    {
                        username = UsernameTextBox.Text,
                        password = Utility.Base64Encode(PasswordBox.Password)
                    };

                    StartDataRefresher();

                    Frame.Navigate(typeof(CorePage));
                }
                catch (Exception e)
                {


                    Frame.Navigate(typeof(MainPage));
                    ShowBox(e.Message);
                }
            }
            _progressWorker.CancelAsync();
        }