Thanks @julian ! 🙂
If I got it right, the plugin nodebb-plugin-category-notifications could solve my issue.
I'd get the result I want if each admin/mod subscribes to all categories, right?
I know there are two default groups, the name is administrator and global moderators (group system) but I do not accidentally delete a group global moderators (it should not be removed) how to I get it back ?
*Sorry if my grammar is bad