Added init core

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

@@ -63,6 +63,7 @@ public class ApplicationEx extends Application {
 
         createNotificationChannels();
         MessageHelper.setSystemProperties();
+        Core.init(this);
     }
 
     private void createNotificationChannels() {

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

@@ -94,6 +94,15 @@ class Core {
     private static final int DOWNLOAD_BATCH_SIZE = 20;
     private static final long YIELD_DURATION = 200L; // milliseconds
 
+    static void init(Context context) {
+        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+        SharedPreferences.Editor editor = prefs.edit();
+        for (String key : prefs.getAll().keySet())
+            if (key.startsWith("notifying:"))
+                editor.remove(key);
+        editor.apply();
+    }
+
     static void processOperations(
             Context context,
             EntityAccount account, EntityFolder folder,