When are scheduled reminders for late registrants to events sent or not sent?

Question

After a small mess over the weekend with an online event login information not being sent, I'm trying to figure out when scheduled reminders are or are not sent for people who register for an event after the reminder was scheduled to send. If I can get some kind of idea what the behaviour is supposed to be, I will test and add this to the documentation.

So, case A: A contact registers after an event scheduled reminder was sent, but before the event starts. Do they receive the reminder? Does it matter how the reminder was set (at a specific date time versus X hours or days before the event starts)?

Case B: A contact registers after an event scheduled reminder was sent, but while the event is happening. Do they receive the reminder? Does it matter how the event was set up, as above?

Case C: A contact is registered for the event after the event ends. Do they receive the past scheduled reminder? Does it matter how the event was set up, as above?

Opinions on what should or does happen seem to be mixed. See other questions here, here, and here. Is there actually a 24 hour test that will send scheduled reminders from 24 hours before the registration but not before? Are there additional rules?

Answer 1

Good question with several permutations! Here's a partial answer from experience.

Case A: A contact registers after an event scheduled reminder was sent, but before the event starts.

It is sent. The timing will be whenever your Send Scheduled Reminders scheduled job runs. It occurs when you set x time before and based on this answer specific time it will not.

Case B: A contact registers after an event scheduled reminder was sent, but while the event is happening.

It is sent.

Case C: A contact is registered for the event after the event ends.

Not sent.

I've not seen a 24 hour test.