SLAs, triggers and Schedules are started on each ticket separately. Thus, there is no easy way to create an email notification for aggregated unassigned tickets with the help of standard SLAs, triggers or Schedules.
I would recommend you to use Microsoft Flow to build this kind of notifications.
You can create a Microsoft Flow that will be started every day.
Then you can query ‘Tickets’ list with the help of “Get Item” action from the SharePoint connector.
Example of usage
Then use ‘Create HTML table’ action from “Data Operations” connector to build an HTML table from results of the query.
Then send generated table to your agents with the help of “Outlook” connector.
You can also request implementation of this Flow from our paid support. Jut drop us a message to email@example.com.