Message Your Group
Group leaders can send inbox messages to an entire group or selected members, control reply options, and customize associated text.
Only available to group leaders.
Similar to writing an email, group leaders can send an inbox message to everyone in the group or just certain people.
You determine who receives replies from your message when you create it. So, if you want to start a group discussion through replies, or just send an announcement with replies disabled, you can do that. If your group has text messaging enabled, you can also customize the text associated with your message.
As a group leader, you are not copied on inbox messages you send.