Check if folders are actually alive

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

@@ -586,6 +586,16 @@ class Core {
         });
     }
 
+    static boolean isAlive(IMAPFolder ifolder) {
+        try {
+            noop(ifolder);
+        } catch (MessagingException ex) {
+            Log.i(ifolder.getFullName(), ex);
+            return false;
+        }
+        return true;
+    }
+
     private static void onSeen(Context context, JSONArray jargs, EntityFolder folder, EntityMessage message, IMAPFolder ifolder) throws MessagingException, JSONException {
         // Mark message (un)seen
         DB db = DB.getInstance(context);

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

@@ -1346,7 +1346,7 @@ public class ServiceSynchronize extends ServiceBase implements SharedPreferences
                                     if (folder.synchronize)
                                         if (!folder.poll && capIdle) {
                                             // Sends folder NOOP
-                                            if (!mapFolders.get(folder).isOpen())
+                                            if (!Core.isAlive(mapFolders.get(folder)))
                                                 throw new StoreClosedException(iservice.getStore(), folder.name);
                                         } else {
                                             if (folder.poll_count == 0)