Virtualmin backup-domain program features?

The Virtualmin backup-domain refers to “features”. This documentation is here:

It’s unclear how to get a list of these features. For example, if I just want to backup and restore email, what would that feature be called? Mail? Email?

Update: I tried specifying “mail” and this backs up accounts, no data. How would I back up mail and data?

I tried googling to find a list of features but no luck so far.

Good question, they need a --feature help command.