Use a different operating system user

Technical assistance
1

I’m installing zammad on Debian 12, and I would like to use _zammad instead of zammad as system user owner of the application and of the service. In fact, my systemd override defines the user _zammad but when I try to run zammad interactively I get this error:

$ zammad
Error: You must be executing as the user 'zammad' or with root privileges to launch commands.
Either log in as 'zammad', root, use sudo, or add sudo privileges for running zammad with your current user.

where does Zammad stores the username allowed to invoke it?

2

The package installation is using the zammad user hard wired. I am not aware of any option to adjust this - except for switching to source code installations. Possibly also possible with container based installation, but I’m not exactly sure on that regard.