To mention someone in a message that you’re in a group, type the "@" symbol and select the contact's name. When you mention someone, a notification will be sent to that contact, indicating to them that they were mentioned.

Note: Mentioning someone in a group will override any mute notifications that contact has set for the group, unless they've muted your individual chat.

If you've been away from a group, you can quickly catch up on messages you were mentioned in or replied to by tapping the "@" button that appears in the bottom corner of the group.