I had a look into this and the interaction setting you selected should be fine, it doesn’t need to be “Everyone” to get the messages tab to show.
There are some additional steps I found that determine if the Messages tab is visible though:
-
User must be signed in as either a group member or an admin
-
User must be a member of a PM enabled group (ie. a member of any groups in
SiteSetting.personal_message_enabled_groups
) - the specific group in question doesn’t have to be in this site setting of group ids, but I think that would be a way to ensure all group members can see the messages tab. -
The group has received at least one messages before
In the case you are experiencing I suspect either 2 or 3 is the issue.
We are also working on the automation script to groups to add an option for sending to individual group members. I will share an more details on that when it is ready.