Hello. Postcards are marked as expired after 3 months. Once they are expired, the sender can mark it as "Mailed" and the recepient ca mark it as "Not Received". Depending on the users actions, an automatic action is taken to resolve the status of that postcard. Registered, canceled or none. Those auto actions are better explained in the first page after login where you also can find the list with the postcards that need your actions.
In this case, you did not marked the postcard as "Mailed" and the recipient mark it as "Not received". In this case, a postcard is canceled. The postcard details are keept in a archive and it will be recreated if the recepient trys to register it. So, postcards can still be registered and you can resend it if it was lost in the postal system.
