We have added the mentions feature for group messages in Messaging. Now you can mention a user by entering the @ symbol and choose the user you want to mention in a group conversation.
1. Click on new group to create a new group message or choose an existing group message.
2. When you enter the message, before you start typing your new message you can mention the user you want to address by entering the @ symbol and choose the user you want to mention in your group conversation.
The same can be done in the mobile app.