Hello, yes. It’s confusing since our post never declined cards and letters (maybe it’s different if someone use P.O. Box), because the postal worker doesn’t always know the update or to which country Pos Udara service is open
Your letters to South Africa and Jamaica will arrive safe 
, but they usually will take more transit time than if you send cards to countries which are serviced by Pos Udara
We can assume that your letters will be kept by Pos Indonesia first until there’s a way to bring them to their destinations. Meanwhile for countries serviced by Pos Udara, the route is open and there are constant flights to those countries to deliver the letters faster
:
We are investigating it.