Filtering the email digest by category

Sorry, I was unclear. I meant, as an admin, is there a way for me to make it so that all future users will receive a certain notification level for a category, without further work on their part?

IE, I want people who sign up to be ‘tracking’ the ‘Announcements’ category, but the ‘Chat’ category is muted by default. (Then they could individually change those settings manually if they cared.)