With a recent update of Soapbox, you are now able to schedule emails to be sent to event participants in the Events app. Participants can include ticket orderers, ticket holders, ticket orderers and ticket holders, and ticket holders of a specific ticket type. Emails can be scheduled for a specific date and time or at a date and time relative to the start date and time of the event.
Upcoming updates will include support for merge fields in the body of the scheduled emails as well as support for the standard email template.
For details on scheduled emails, check out Scheduling emails to be sent to event participants.