Use the Bell icon to configure notifications whithin your channel or room. Other preferences are available in the
Personel Settings dialog. Make sure your preferences include Receiving unread messages to get notifications.
Upon starting Rocket.Chat, you are asked to allow desktop notifications. Notifications appear as small boxes on the right corner, depending on the general or per-room settings.
Depending on your settings per room or channel, you receive notifications on your mobile device for all messages or only if somebody mentions you. Notifications in rooms are only sent when the desktop client goes with no use for more than five minutes. Currently, changing your status to "Away" does not speed up the countdown.
Depending on the privacy settings set by the administrator, you will see the sender, room name or the first line of the message as a notification on your mobile device.
Notifications of direct messages or mentions by @username are sent by Email to your E-Mail address, but only if no web-client is connected.
@username - notifies this person @all - notifies all members of this room or channel @here - notifies all members of this room or channel who are online