Yes, refer to ns8-mail/README.md at main · NethServer/ns8-mail · GitHub
As said by Markus, enter the app agent enviroment with
runagent -m mail1
As always I suggest to avoid writing directly into system absolute paths with some “_data” path components, because it may have ownership and SELinux implications. The safe approach is to use Podman commands, like “podman exec”.
In case of mail you can get an interactive shell in the Postfix container with
podman exec -ti postfix ash -l