Automatic checkout receipts?

[orenyk]

Inspired by the recent cron outage, we've been asked to automatically send checkout receipts to serve as a backup checkin reminder e-mail. We recently re-enabled those e-mails in #665, so having them sent on checkout would be trivial; the question is whether we want to be adding more automatic e-mails to our UX or if it's better to be optional. This really ties into #914, but that's much larger in scope.