ramjke yep, its very strange really that Flarum doesnt have it by default, especially for admins.
However Flarum do a huge progress in last two years (not only Flarum, sure, many extensions have a huge progress doned by their authors and community members), hope some new notification will be added soon. I am using PWA by @askvortsov and his PUSH-notification. I am disabled all kind of emails for me (administrator) and use only PUSH, see the warnings when visit. The only way for seening new discussion is checking of the all discussion list (url forum/all) which is not so suitable for fast reacting.
Activating FoF Follow Tags and FoF Subscribed do the things but brokes new user registration when limit for emails is gone. Maybe this can be fixed if Flarum will have some general presets for notifications for each groups of users or some tools for customisation of the default notification settings.
I'd checked the base and see this parameters (in some BLOB), but didn't yet create a script for this (disabling email notifications).