Effective Aug 1st 2022, we have stopped using password-protected compressed files (PPAP) and have switched to using Mimecast* file transmission when sending files externally.
Please refer to the following URL for information on how to receive files sent in this way.
https://nttcdd.jp/en/wp-content/uploads/sites/2/2023/09/How-to-receive-files-sent-via-Mimecastfor-external-useEN.pdf
*Mimecast is a cloud-based integrated Email security service offered by Mimecast Ltd that provides increased security and integrity of files sent via Email.