Mortgaging. The insurers shall be liable towards mortgages whose claims are not covered by the debtor's as- sets up to the amount of the indemnity, provided the mortgage: - is entered in the land register or - has been notified to the insurers in writing. This shall equally apply whenever the rightful claimant has forfeited his right to indemnity in full or in part. This provision shall not be applied where the mortgagee is himself a rightful claimant or where he has caused the loss or damage inten- tionally or through gross negligence.