Ok! purtroppo non ho modificato il messaggio prima di 60 minuti e quindi lo riposrto indentato in un nuovo messaggio:
codice:
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;

public class prova {

	private final String USER_AGENT = "Mozilla/5.0";

	public static void main(String[] args) throws Exception {

		prova http = new prova();

		System.out.println("Send Http POST request");
		http.sendPost();

	}

	// HTTP POST request
	private void sendPost() throws Exception {

		String url = "https://areaclienti3.tre.it/login_133.jsp?service=https%3A%2F%2Fareaclienti3.tre.it%2F133%2Fprofilo.jsp&lt=LT-11962399-NAXtCKUqT3ATw9PcUvSGgmwEnfYEvN&flowExecutionKey=e1s1";

		HttpClient client = new DefaultHttpClient();
		HttpPost post = new HttpPost(url);

		// add header
		post.setHeader("User-Agent", USER_AGENT);

		List<NameValuePair> urlParameters = new ArrayList<NameValuePair>();
		urlParameters.add(new BasicNameValuePair("username1", "33********"));
		urlParameters.add(new BasicNameValuePair("password", "PASSWORD"));

		post.setEntity(new UrlEncodedFormEntity(urlParameters));

		HttpResponse response = client.execute(post);
		System.out.println("\nSending 'POST' request to URL : " + url);
		System.out.println("Post parameters : " + post.getEntity());
		System.out.println("Response Code : "
				+ response.getStatusLine().getStatusCode());

		BufferedReader rd = new BufferedReader(new InputStreamReader(response
				.getEntity().getContent()));

		StringBuffer result = new StringBuffer();
		String line = "";
		while ((line = rd.readLine()) != null) {
			result.append(line);
		}

		System.out.println(result.toString());

	}

}