Email Text :- It is possible to use the same details (URL) as in the Plain Text box above. Template variables can be used [[Template_Variables| see here]]
It is assumed you use the Checkin/Checkout feature in the Dashboard, if not you can either manually add Checkout to your bookings (Booking info tab) or create an auto action to add the Booking Info Codes to the bookings.
If you send Emails with pdf attachment (invoice, booking template) to Alias-Email addresses created by channels the channel might block the attachment so it is not delivered to the guest. Ask your channel about their policy regarding this.