I am still getting familiar with the intricacies of Discourse.
Is it possible to set up an “Announcements” category so that when posting there, every registered user will receive a (preferably email) notification by default, but users also have the option to unsubscribe, if they wish to?
We have a Discourse forum for a software tool, and are looking to announce (infrequent) new releases this way.
In your site settings, there is a default categories watching first post setting. You can add an announcements category to that list, and then all users will receive a notification for any new topics. Any user can use the Discourse UI, or the email unsubscribe link to opt-out of those notifications.
You will probably want to change the security settings on that category so that only trusted staff can create new topics.