Edit: @Successful_Try543@feddit.org solved it. It says “one special character”. Not “at least one”.

    • Successful_Try543
      link
      fedilink
      arrow-up
      5
      ·
      2 months ago

      It was not special from the outside, but from the inside. It was either the envelope or the TAN list that was printed with a special pattern to prevent reading the list by using a flashlight.