Editing teachers should have an option of posting to all groups at once

I'm not sure this is a bug or a misunderstood feature.

Preliminary:

I've assigned myself (the admin account) as a teacher of a course. I have three visible groups being forced for the course. I have three sections. I want them to be able to see each other, but by having them in groups it makes it easier for me to manage all 60+ students.

Issue:

I want to be able to (as Teacher or Admin) make a post to the News forum for the course and have the message emailed to all groups. The way I see it, with the groups setup like I have them, mail will only go to the users in the group I belong to.