Even if you have written your name on the koden-bukuro (outer envelope), you should write your address, including the post code, and name again on the rear of the naka-bukuro.
たとえ香典袋（外側の袋）に氏名などを書いたとしても、中袋には住所や氏名を郵便番号を含めきちんと書いておく。