How can you use RSVPify's automatic email reminders feature?
You can find & customize automatic reminders by going to setup > email confirmations & reminders.
If enabled, all your attending guests will receive up to 2 email reminders before the actual event, and you can set how long before your event do the guests receive the reminder(s) - from 7 days in advance to just 1 hour prior to the event.
Email reminders look similar to the confirmation email, but you can change the subject line, and add different text content
And if you are not sure how to customize your confirmation emails the good place to start would be HERE.