When you save a new reservation, this option will automatically send the predefined confirmation letter, eliminating the need to manually go to the toolbox and click "Confirm Letter.
Path: Management > Setup > Property > Forms
Check the box "Automatically Send Confirmation".

This automated email feature sends confirmation letters but not cancellation letters, and only for reservations made through "Front Office > Reservation > Add Res." For reservations created through "BookRes," you'll need to manually send the confirmation letter by selecting "Confirm Letter" within Add Res.