Yes, you can send reminders (before rental) and promotional or thank-you emails after rental in Settings / Notifications by clicking Add message to be sent after or ahead of time. You have 6 different spots you can fill with different times. These times can be relative to the rental start time, end time or also time of the reservation. This lets you send emails to clients also X days after the reservation is made, for example in order to remind them about the payment they must make. Please note that all you can use the same feature to send reminders to the administrator, moderator or resource admin, for example as a reminder of an action they should do.