Revert "Revert "Auto full text search when no FTS matches""

This reverts commit a2fb08e02e.

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

@@ -325,7 +325,8 @@ public class BoundaryCallbackMessages extends PagedList.BoundaryCallback<TupleMe
                 db.endTransaction();
             }
 
-            return found;
+            if (state.ids.size() > 0)
+                return found;
         }
 
         while (found < pageSize && !state.destroyed) {