How to notify all users of post

As admin I have an announcement to make to all users of our platform. How can I post a new message and notify all users?

Click the wrench on the topic and pin it globally.

Thanks but what I want is to alert all users, not just those who are active today. I note from another thread from 2015 you don’t have a feature for emailing/messaging all users? That would be a really needed feature. Otherwise you can’t reach out to the less active users.