There are four different categories that can be assigned to a One Time Message: ‘Administrative’, ‘Financial’, ‘Marketing’, or ‘Emergency’. For ‘Administrative’,’ Marketing’, and ‘Emergency’ messages you can choose to send them to All Guests Currently Checked In, All Guests Checking In on a specified date(s), All Guests Checking Out on a specified date(s), or a specific reservation. Financial message can only be sent to a specific reservation.
An additional option for One Time Messages that is not available in the Event Messaging is the time/date of delivery. You can select to have your message sent now, or later. (Emergency messages and Financial Messages can only be sent ‘Now’.) For the messages you choose to send ‘Later’, the list of recipients is generated just before the message is sent, not when the message is created just in case a reservation is made or canceled between the times the message was created and when it gets sent. More details in section
3.5 - Manual Messages below.