You can now use the API to send broadcasts to your users on your channel of choice. Previously, you had to manually login to the platform and add your targets in the channel's settings page, as shown below.
This is very easy to use, but does not allow for automatisation. With this update you can now perform HTTP requests to create broadcasts programmatically.
Please refer to the documentation to learn more about the Broadcasts API.
Of course, you can still send broadcasts from the interface!
Each channel has its set of features and limitations. For example Messenger and MS Teams only allow sending to users that have already interacted with your bot before.