Send registered no-shows a recap with next year's early access

Pull the list of people who registered but did not check in, and send them a short recap email with a highlight video or top takeaways, along with early access to register for next year's event before public registration opens. Send it within a week of the event ending.

Why it works: A no-show is still an interested lead, and giving them the recap plus a head start keeps them from forgetting the event entirely.