Skip idle for transient accounts

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

@@ -1288,6 +1288,7 @@ public class ServiceSynchronize extends ServiceBase implements SharedPreferences
                             });
 
                             // Idle folder
+                            if (!isTransient(account)) {
                                 Thread idler = new Thread(new Runnable() {
                                     @Override
                                     public void run() {
@@ -1312,6 +1313,7 @@ public class ServiceSynchronize extends ServiceBase implements SharedPreferences
                                 idler.setPriority(THREAD_PRIORITY_BACKGROUND);
                                 idler.start();
                                 idlers.add(idler);
+                            }
 
                             if (sync && folder.selectable)
                                 EntityOperation.sync(this, folder.id, false, force && !forced);