Need help with software selection

Hello. I think what I need is really simple but I cannot seem to find it. I have a tourist based business and I want to send automated emails to my clients before, during, and after their stay based upon their check-in and check-out dates. Basically I want to enter their name, email, and dates into the software, then it auto-schedules and sends pre-formatted emails to them at various times (one day before arrival, one day after departure, etc.)

Any help?