You could create a group "all" which is private - hidden - no tags.
Every user is member of this group. So you cloud mention the group @all where all users are members.
Hi I have seen old topics that we can allow unregistered users to create topics, or reply to them. But I'm in version 1.9.3 and cannot find the correct settings for that. I have allowed guest chat in privileges settings but still unregistered users cannot create or reply to topics. How to allow these permissions?
In ACP > Manage > Privileges, select the category you want to allow guests to post in, and give guests the "Create Topics" and "Reply to Topics" privileges.