Update JavaFX 8 UI / Multithread

for days now i am trying to update a Javafx userinterface while sending 2 or more E-Mails automatically. The UI should update a Label with "connecting", "sending" and "sent". I've read about Runnables, Tasks, TimeLine but i dont really understand which method i should use and how it works.

Everywhere i read about Platform.runLater(), I used it but the animation in my JavaFX Gui freezes and the Label only changes, when all E-Mails have been sent.

I will update this post with my code soon, but can someone already tell me what kind of Thread i should use and how the ui can be updated easily?

//edit

thanks for your help, Branislav but now im getting the "Not on FX application thread"-Error. The following code is not my "extends Application"-class, please take a look.

public class ControllerOCM implements Initializable{



    @FXML
    private ComboBox<String> comboEmpf;

    @FXML
    private Label lblStatus;

    @FXML
    private Label lblStatus1;


    @Override
    public void initialize(URL location, ResourceBundle resources) {
        hint.setText("some hint");
    }

    public void sende(ActionEvent event) throws Exception {

        switch (comboEmpf.getValue()) {
        case "A": System.out.println("A");break;
        case "B":
        File fTEST = new File("C:\\B\\");
        File[] fpathTEST = fTEST.listFiles();
        String[] fnameTEST = fTEST.list();

    for (int i=0; i<fpathTEST.length; i++) {
        SendenTask sendTEST = new SendenTask(mail@address.com,
                "bodycontent",
                "subject", 
                fpathTEST[i].toString(),    
                fnameTEST[i],               
                i,                      //count
                fpathTEST.length);      //max

        new Thread(sendTEST).start();
    }
            break;
        }
    }

     public class SendenTask extends Task<Void> {
            private String adr;
            private String body;
            private String subj;
            private String fp;
            private String fn;
            private int count;
            private int max;

         public SendenTask(String adr, String body, String subj, String fp, String fn, int count, int max) {
            this.adr = adr;
            this.body = body;
            this.subj = subj;
            this.fp = fp;
            this.fn = fn;
            this.count = count;
            this.max = max;

         }

         @Override 
         protected Void call() throws Exception {

         lblStatus1.setText("connecting");
         //doing connectionAction

         lblStatus1.setText("sending");
         updateMessage("sending");
         //doing sendingthingys


         //sending complete
         lblStatus1.setText("sent");
         System.out.println("done");
         updateMessage("done");

             return null;
         }
     }





}

via Chebli Mohamed