When a user is offline, incoming messages are stored for them as offline messages. By default, these messages are stored for 7 days, and the user receives them upon their next login. You can configure the storage duration from 1 to 7 days.
This setting only applies to one-to-one chats, group chats, and system conversations.
You can configure this setting on the Basic Features page in the Console, under Offline message storage duration.
If you have any questions about this feature, feel free to submit a ticket to us.