Ignore unknown host for unsubscribe

app/src/main/java/eu/faircode/email/FragmentDialogUnsubscribe.java

@@ -42,6 +42,7 @@ import java.io.IOException;
 import java.net.HttpURLConnection;
 import java.net.URL;
 import java.net.URLDecoder;
+import java.net.UnknownHostException;
 import java.nio.charset.StandardCharsets;
 
 public class FragmentDialogUnsubscribe extends FragmentDialogBase {
@@ -162,11 +163,12 @@ public class FragmentDialogUnsubscribe extends FragmentDialogBase {
                         if (ex instanceof IllegalStateException)
                             ToastEx.makeText(context, ex.getMessage(), Toast.LENGTH_LONG).show();
                         else if (ex instanceof IllegalArgumentException || ex instanceof IOException)
+                            if (!(ex instanceof UnknownHostException)) {
                                 ToastEx.makeText(context,
                                         context.getString(R.string.title_unsubscribe_error,
                                                 Log.formatThrowable(ex, false)),
                                         Toast.LENGTH_LONG).show();
-                        else
+                            } else
                                 Log.unexpectedError(getParentFragmentManager(), ex);
                     }
                 }.execute(FragmentDialogUnsubscribe.this, args, "unsubscribe");